puzzles: refactor and resync with upstream

This brings puzzles up-to-date with upstream revision
2d333750272c3967cfd5cd3677572cddeaad5932, though certain changes made
by me, including cursor-only Untangle and some compilation fixes
remain. Upstream code has been moved to its separate subdirectory and
future syncs can be done by simply copying over the new sources.

Change-Id: Ia6506ca5f78c3627165ea6791d38db414ace0804

1 files changed, 2267 insertions, 0 deletions

diff --git a/apps/plugins/puzzles/src/unequal.c b/apps/plugins/puzzles/src/unequal.c
new file mode 100644
index 0000000000..a63b7d8ed0
--- /dev/null
+++ b/apps/plugins/puzzles/src/unequal.c
@@ -0,0 +1,2267 @@
+/*
+ * unequal.c
+ *
+ * Implementation of 'Futoshiki', a puzzle featured in the Guardian.
+ *
+ * TTD:
+   * add multiple-links-on-same-col/row solver nous
+   * Optimise set solver to use bit operations instead
+ *
+ * Guardian puzzles of note:
+   * #1: 5:0,0L,0L,0,0,0R,0,0L,0D,0L,0R,0,2,0D,0,0,0,0,0,0,0U,0,0,0,0U,
+   * #2: 5:0,0,0,4L,0L,0,2LU,0L,0U,0,0,0U,0,0,0,0,0D,0,3LRUD,0,0R,3,0L,0,0,
+   * #3: (reprint of #2)
+   * #4: 
+   * #5: 5:0,0,0,0,0,0,2,0U,3U,0U,0,0,3,0,0,0,3,0D,4,0,0,0L,0R,0,0,
+   * #6: 5:0D,0L,0,0R,0,0,0D,0,3,0D,0,0R,0,0R,0D,0U,0L,0,1,2,0,0,0U,0,0L,
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <ctype.h>
+#include <math.h>
+
+#include "puzzles.h"
+#include "latin.h" /* contains typedef for digit */
+
+/* ----------------------------------------------------------
+ * Constant and structure definitions
+ */
+
+#define FLASH_TIME 0.4F
+
+#define PREFERRED_TILE_SIZE 32
+
+#define TILE_SIZE (ds->tilesize)
+#define GAP_SIZE  (TILE_SIZE/2)
+#define SQUARE_SIZE (TILE_SIZE + GAP_SIZE)
+
+#define BORDER    (TILE_SIZE / 2)
+
+#define COORD(x)  ( (x) * SQUARE_SIZE + BORDER )
+#define FROMCOORD(x)  ( ((x) - BORDER + SQUARE_SIZE) / SQUARE_SIZE - 1 )
+
+#define GRID(p,w,x,y) ((p)->w[((y)*(p)->order)+(x)])
+#define GRID3(p,w,x,y,z) ((p)->w[ (((x)*(p)->order+(y))*(p)->order+(z)) ])
+#define HINT(p,x,y,n) GRID3(p, hints, x, y, n)
+
+enum {
+    COL_BACKGROUND,
+    COL_GRID,
+    COL_TEXT, COL_GUESS, COL_ERROR, COL_PENCIL,
+    COL_HIGHLIGHT, COL_LOWLIGHT, COL_SPENT = COL_LOWLIGHT,
+    NCOLOURS
+};
+
+struct game_params {
+    int order;          /* Size of latin square */
+    int diff;           /* Difficulty */
+    int adjacent;       /* Puzzle indicators are 'adjacent number'
+                            not 'greater-than'. */
+};
+
+#define F_IMMUTABLE     1       /* passed in as game description */
+#define F_ADJ_UP        2
+#define F_ADJ_RIGHT     4
+#define F_ADJ_DOWN      8
+#define F_ADJ_LEFT      16
+#define F_ERROR         32
+#define F_ERROR_UP      64
+#define F_ERROR_RIGHT   128
+#define F_ERROR_DOWN    256
+#define F_ERROR_LEFT    512
+#define F_SPENT_UP      1024
+#define F_SPENT_RIGHT   2048
+#define F_SPENT_DOWN    4096
+#define F_SPENT_LEFT    8192
+
+#define ADJ_TO_SPENT(x) ((x) << 9)
+
+#define F_ERROR_MASK (F_ERROR|F_ERROR_UP|F_ERROR_RIGHT|F_ERROR_DOWN|F_ERROR_LEFT)
+
+struct game_state {
+    int order, completed, cheated, adjacent;
+    digit *nums;                 /* actual numbers (size order^2) */
+    unsigned char *hints;        /* remaining possiblities (size order^3) */
+    unsigned int *flags;         /* flags (size order^2) */
+};
+
+/* ----------------------------------------------------------
+ * Game parameters and presets
+ */
+
+/* Steal the method from map.c for difficulty levels. */
+#define DIFFLIST(A)               \
+    A(LATIN,Trivial,NULL,t)       \
+    A(EASY,Easy,solver_easy, e)   \
+    A(SET,Tricky,solver_set, k)   \
+    A(EXTREME,Extreme,NULL,x)     \
+    A(RECURSIVE,Recursive,NULL,r)
+
+#define ENUM(upper,title,func,lower) DIFF_ ## upper,
+#define TITLE(upper,title,func,lower) #title,
+#define ENCODE(upper,title,func,lower) #lower
+#define CONFIG(upper,title,func,lower) ":" #title
+enum { DIFFLIST(ENUM) DIFFCOUNT, DIFF_IMPOSSIBLE = diff_impossible, DIFF_AMBIGUOUS = diff_ambiguous, DIFF_UNFINISHED = diff_unfinished };
+static char const *const unequal_diffnames[] = { DIFFLIST(TITLE) };
+static char const unequal_diffchars[] = DIFFLIST(ENCODE);
+#define DIFFCONFIG DIFFLIST(CONFIG)
+
+#define DEFAULT_PRESET 0
+
+const static struct game_params unequal_presets[] = {
+    {  4, DIFF_EASY,    0 },
+    {  5, DIFF_EASY,    0 },
+    {  5, DIFF_SET,     0 },
+    {  5, DIFF_SET,     1 },
+    {  5, DIFF_EXTREME, 0 },
+    {  6, DIFF_EASY,    0 },
+    {  6, DIFF_SET,     0 },
+    {  6, DIFF_SET,     1 },
+    {  6, DIFF_EXTREME, 0 },
+    {  7, DIFF_SET,     0 },
+    {  7, DIFF_SET,     1 },
+    {  7, DIFF_EXTREME, 0 }
+};
+
+static int game_fetch_preset(int i, char **name, game_params **params)
+{
+    game_params *ret;
+    char buf[80];
+
+    if (i < 0 || i >= lenof(unequal_presets))
+        return FALSE;
+
+    ret = snew(game_params);
+    *ret = unequal_presets[i]; /* structure copy */
+
+    sprintf(buf, "%s: %dx%d %s",
+            ret->adjacent ? "Adjacent" : "Unequal",
+            ret->order, ret->order,
+            unequal_diffnames[ret->diff]);
+
+    *name = dupstr(buf);
+    *params = ret;
+    return TRUE;
+}
+
+static game_params *default_params(void)
+{
+    game_params *ret;
+    char *name;
+
+    if (!game_fetch_preset(DEFAULT_PRESET, &name, &ret)) return NULL;
+    sfree(name);
+    return ret;
+}
+
+static void free_params(game_params *params)
+{
+    sfree(params);
+}
+
+static game_params *dup_params(const game_params *params)
+{
+    game_params *ret = snew(game_params);
+    *ret = *params;       /* structure copy */
+    return ret;
+}
+
+static void decode_params(game_params *ret, char const *string)
+{
+    char const *p = string;
+
+    ret->order = atoi(p);
+    while (*p && isdigit((unsigned char)*p)) p++;
+
+    if (*p == 'a') {
+        p++;
+        ret->adjacent = 1;
+    } else
+        ret->adjacent = 0;
+
+    if (*p == 'd') {
+        int i;
+        p++;
+        ret->diff = DIFFCOUNT+1; /* ...which is invalid */
+        if (*p) {
+            for (i = 0; i < DIFFCOUNT; i++) {
+                if (*p == unequal_diffchars[i])
+                    ret->diff = i;
+            }
+            p++;
+        }
+    }
+}
+
+static char *encode_params(const game_params *params, int full)
+{
+    char ret[80];
+
+    sprintf(ret, "%d", params->order);
+    if (params->adjacent)
+        sprintf(ret + strlen(ret), "a");
+    if (full)
+        sprintf(ret + strlen(ret), "d%c", unequal_diffchars[params->diff]);
+
+    return dupstr(ret);
+}
+
+static config_item *game_configure(const game_params *params)
+{
+    config_item *ret;
+    char buf[80];
+
+    ret = snewn(4, config_item);
+
+    ret[0].name = "Mode";
+    ret[0].type = C_CHOICES;
+    ret[0].sval = ":Unequal:Adjacent";
+    ret[0].ival = params->adjacent;
+
+    ret[1].name = "Size (s*s)";
+    ret[1].type = C_STRING;
+    sprintf(buf, "%d", params->order);
+    ret[1].sval = dupstr(buf);
+    ret[1].ival = 0;
+
+    ret[2].name = "Difficulty";
+    ret[2].type = C_CHOICES;
+    ret[2].sval = DIFFCONFIG;
+    ret[2].ival = params->diff;
+
+    ret[3].name = NULL;
+    ret[3].type = C_END;
+    ret[3].sval = NULL;
+    ret[3].ival = 0;
+
+    return ret;
+}
+
+static game_params *custom_params(const config_item *cfg)
+{
+    game_params *ret = snew(game_params);
+
+    ret->adjacent = cfg[0].ival;
+    ret->order = atoi(cfg[1].sval);
+    ret->diff = cfg[2].ival;
+
+    return ret;
+}
+
+static char *validate_params(const game_params *params, int full)
+{
+    if (params->order < 3 || params->order > 32)
+        return "Order must be between 3 and 32";
+    if (params->diff >= DIFFCOUNT)
+        return "Unknown difficulty rating";
+    if (params->order < 5 && params->adjacent &&
+        params->diff >= DIFF_SET)
+        return "Order must be at least 5 for Adjacent puzzles of this difficulty.";
+    return NULL;
+}
+
+/* ----------------------------------------------------------
+ * Various utility functions
+ */
+
+static const struct { unsigned int f, fo, fe; int dx, dy; char c, ac; } adjthan[] = {
+    { F_ADJ_UP,    F_ADJ_DOWN,  F_ERROR_UP,     0, -1, '^', '-' },
+    { F_ADJ_RIGHT, F_ADJ_LEFT,  F_ERROR_RIGHT,  1,  0, '>', '|' },
+    { F_ADJ_DOWN,  F_ADJ_UP,    F_ERROR_DOWN,   0,  1, 'v', '-' },
+    { F_ADJ_LEFT,  F_ADJ_RIGHT, F_ERROR_LEFT,  -1,  0, '<', '|' }
+};
+
+static game_state *blank_game(int order, int adjacent)
+{
+    game_state *state = snew(game_state);
+    int o2 = order*order, o3 = o2*order;
+
+    state->order = order;
+    state->adjacent = adjacent;
+    state->completed = state->cheated = 0;
+
+    state->nums = snewn(o2, digit);
+    state->hints = snewn(o3, unsigned char);
+    state->flags = snewn(o2, unsigned int);
+
+    memset(state->nums, 0, o2 * sizeof(digit));
+    memset(state->hints, 0, o3);
+    memset(state->flags, 0, o2 * sizeof(unsigned int));
+
+    return state;
+}
+
+static game_state *dup_game(const game_state *state)
+{
+    game_state *ret = blank_game(state->order, state->adjacent);
+    int o2 = state->order*state->order, o3 = o2*state->order;
+
+    memcpy(ret->nums, state->nums, o2 * sizeof(digit));
+    memcpy(ret->hints, state->hints, o3);
+    memcpy(ret->flags, state->flags, o2 * sizeof(unsigned int));
+
+    return ret;
+}
+
+static void free_game(game_state *state)
+{
+    sfree(state->nums);
+    sfree(state->hints);
+    sfree(state->flags);
+    sfree(state);
+}
+
+#define CHECKG(x,y) grid[(y)*o+(x)]
+
+/* Returns 0 if it finds an error, 1 otherwise. */
+static int check_num_adj(digit *grid, game_state *state,
+                        int x, int y, int me)
+{
+    unsigned int f = GRID(state, flags, x, y);
+    int ret = 1, i, o = state->order;
+
+    for (i = 0; i < 4; i++) {
+        int dx = adjthan[i].dx, dy = adjthan[i].dy, n, dn;
+
+        if (x+dx < 0 || x+dx >= o || y+dy < 0 || y+dy >= o)
+            continue;
+
+        n = CHECKG(x, y);
+        dn = CHECKG(x+dx, y+dy);
+
+        assert (n != 0);
+        if (dn == 0) continue;
+
+        if (state->adjacent) {
+            int gd = abs(n-dn);
+
+            if ((f & adjthan[i].f) && (gd != 1)) {
+                debug(("check_adj error (%d,%d):%d should be | (%d,%d):%d",
+                       x, y, n, x+dx, y+dy, dn));
+                if (me) GRID(state, flags, x, y) |= adjthan[i].fe;
+                ret = 0;
+            }
+            if (!(f & adjthan[i].f) && (gd == 1)) {
+                debug(("check_adj error (%d,%d):%d should not be | (%d,%d):%d",
+                       x, y, n, x+dx, y+dy, dn));
+                if (me) GRID(state, flags, x, y) |= adjthan[i].fe;
+                ret = 0;
+            }
+
+        } else {
+            if ((f & adjthan[i].f) && (n <= dn)) {
+                debug(("check_adj error (%d,%d):%d not > (%d,%d):%d",
+                       x, y, n, x+dx, y+dy, dn));
+                if (me) GRID(state, flags, x, y) |= adjthan[i].fe;
+                ret = 0;
+            }
+        }
+    }
+    return ret;
+}
+
+/* Returns 0 if it finds an error, 1 otherwise. */
+static int check_num_error(digit *grid, game_state *state,
+                           int x, int y, int mark_errors)
+{
+    int o = state->order;
+    int xx, yy, val = CHECKG(x,y), ret = 1;
+
+    assert(val != 0);
+
+    /* check for dups in same column. */
+    for (yy = 0; yy < state->order; yy++) {
+        if (yy == y) continue;
+        if (CHECKG(x,yy) == val) ret = 0;
+    }
+
+    /* check for dups in same row. */
+    for (xx = 0; xx < state->order; xx++) {
+        if (xx == x) continue;
+        if (CHECKG(xx,y) == val) ret = 0;
+    }
+
+    if (!ret) {
+        debug(("check_num_error (%d,%d) duplicate %d", x, y, val));
+        if (mark_errors) GRID(state, flags, x, y) |= F_ERROR;
+    }
+    return ret;
+}
+
+/* Returns:     -1 for 'wrong'
+ *               0 for 'incomplete'
+ *               1 for 'complete and correct'
+ */
+static int check_complete(digit *grid, game_state *state, int mark_errors)
+{
+    int x, y, ret = 1, o = state->order;
+
+    if (mark_errors)
+        assert(grid == state->nums);
+
+    for (x = 0; x < state->order; x++) {
+        for (y = 0; y < state->order; y++) {
+            if (mark_errors)
+                GRID(state, flags, x, y) &= ~F_ERROR_MASK;
+            if (grid[y*o+x] == 0) {
+                ret = 0;
+            } else {
+                if (!check_num_error(grid, state, x, y, mark_errors)) ret = -1;
+                if (!check_num_adj(grid, state, x, y, mark_errors)) ret = -1;
+            }
+        }
+    }
+    if (ret == 1 && latin_check(grid, o))
+        ret = -1;
+    return ret;
+}
+
+static char n2c(digit n, int order) {
+    if (n == 0)         return ' ';
+    if (order < 10) {
+        if (n < 10)     return '0' + n;
+    } else {
+        if (n < 11)     return '0' + n-1;
+        n -= 11;
+        if (n <= 26)    return 'A' + n;
+    }
+    return '?';
+}
+
+/* should be 'digit', but includes -1 for 'not a digit'.
+ * Includes keypresses (0 especially) for interpret_move. */
+static int c2n(int c, int order) {
+    if (c < 0 || c > 0xff)
+        return -1;
+    if (c == ' ' || c == '\b')
+        return 0;
+    if (order < 10) {
+        if (c >= '0' && c <= '9')
+            return (int)(c - '0');
+    } else {
+        if (c >= '0' && c <= '9')
+            return (int)(c - '0' + 1);
+        if (c >= 'A' && c <= 'Z')
+            return (int)(c - 'A' + 11);
+        if (c >= 'a' && c <= 'z')
+            return (int)(c - 'a' + 11);
+    }
+    return -1;
+}
+
+static int game_can_format_as_text_now(const game_params *params)
+{
+    return TRUE;
+}
+
+static char *game_text_format(const game_state *state)
+{
+    int x, y, len, n;
+    char *ret, *p;
+
+    len = (state->order*2) * (state->order*2-1) + 1;
+    ret = snewn(len, char);
+    p = ret;
+
+    for (y = 0; y < state->order; y++) {
+        for (x = 0; x < state->order; x++) {
+            n = GRID(state, nums, x, y);
+            *p++ = n > 0 ? n2c(n, state->order) : '.';
+
+            if (x < (state->order-1)) {
+                if (state->adjacent) {
+                    *p++ = (GRID(state, flags, x, y) & F_ADJ_RIGHT) ? '|' : ' ';
+                } else {
+                    if (GRID(state, flags, x, y) & F_ADJ_RIGHT)
+                        *p++ = '>';
+                    else if (GRID(state, flags, x+1, y) & F_ADJ_LEFT)
+                        *p++ = '<';
+                    else
+                        *p++ = ' ';
+                }
+            }
+        }
+        *p++ = '\n';
+
+        if (y < (state->order-1)) {
+            for (x = 0; x < state->order; x++) {
+                if (state->adjacent) {
+                    *p++ = (GRID(state, flags, x, y) & F_ADJ_DOWN) ? '-' : ' ';
+                } else {
+                    if (GRID(state, flags, x, y) & F_ADJ_DOWN)
+                        *p++ = 'v';
+                    else if (GRID(state, flags, x, y+1) & F_ADJ_UP)
+                        *p++ = '^';
+                    else
+                        *p++ = ' ';
+                }
+
+                if (x < state->order-1)
+                  *p++ = ' ';
+            }
+            *p++ = '\n';
+        }
+    }
+    *p++ = '\0';
+
+    assert(p - ret == len);
+    return ret;
+}
+
+#ifdef STANDALONE_SOLVER
+static void game_debug(game_state *state)
+{
+    char *dbg = game_text_format(state);
+    printf("%s", dbg);
+    sfree(dbg);
+}
+#endif
+
+/* ----------------------------------------------------------
+ * Solver.
+ */
+
+struct solver_link {
+    int len, gx, gy, lx, ly;
+};
+
+struct solver_ctx {
+    game_state *state;
+
+    int nlinks, alinks;
+    struct solver_link *links;
+};
+
+static void solver_add_link(struct solver_ctx *ctx,
+                            int gx, int gy, int lx, int ly, int len)
+{
+    if (ctx->alinks < ctx->nlinks+1) {
+        ctx->alinks = ctx->alinks*2 + 1;
+        /*debug(("resizing ctx->links, new size %d", ctx->alinks));*/
+        ctx->links = sresize(ctx->links, ctx->alinks, struct solver_link);
+    }
+    ctx->links[ctx->nlinks].gx = gx;
+    ctx->links[ctx->nlinks].gy = gy;
+    ctx->links[ctx->nlinks].lx = lx;
+    ctx->links[ctx->nlinks].ly = ly;
+    ctx->links[ctx->nlinks].len = len;
+    ctx->nlinks++;
+    /*debug(("Adding new link: len %d (%d,%d) < (%d,%d), nlinks now %d",
+           len, lx, ly, gx, gy, ctx->nlinks));*/
+}
+
+static struct solver_ctx *new_ctx(game_state *state)
+{
+    struct solver_ctx *ctx = snew(struct solver_ctx);
+    int o = state->order;
+    int i, x, y;
+    unsigned int f;
+
+    ctx->nlinks = ctx->alinks = 0;
+    ctx->links = NULL;
+    ctx->state = state;
+
+    if (state->adjacent) return ctx; /* adjacent mode doesn't use links. */
+
+    for (x = 0; x < o; x++) {
+        for (y = 0; y < o; y++) {
+            f = GRID(state, flags, x, y);
+            for (i = 0; i < 4; i++) {
+                if (f & adjthan[i].f)
+                    solver_add_link(ctx, x, y, x+adjthan[i].dx, y+adjthan[i].dy, 1);
+            }
+        }
+    }
+
+    return ctx;
+}
+
+static void *clone_ctx(void *vctx)
+{
+    struct solver_ctx *ctx = (struct solver_ctx *)vctx;
+    return new_ctx(ctx->state);
+}
+
+static void free_ctx(void *vctx)
+{
+    struct solver_ctx *ctx = (struct solver_ctx *)vctx;
+    if (ctx->links) sfree(ctx->links);
+    sfree(ctx);
+}
+
+static void solver_nminmax(struct latin_solver *solver,
+                           int x, int y, int *min_r, int *max_r,
+                           unsigned char **ns_r)
+{
+    int o = solver->o, min = o, max = 0, n;
+    unsigned char *ns;
+
+    assert(x >= 0 && y >= 0 && x < o && y < o);
+
+    ns = solver->cube + cubepos(x,y,1);
+
+    if (grid(x,y) > 0) {
+        min = max = grid(x,y)-1;
+    } else {
+        for (n = 0; n < o; n++) {
+            if (ns[n]) {
+                if (n > max) max = n;
+                if (n < min) min = n;
+            }
+        }
+    }
+    if (min_r) *min_r = min;
+    if (max_r) *max_r = max;
+    if (ns_r) *ns_r = ns;
+}
+
+static int solver_links(struct latin_solver *solver, void *vctx)
+{
+    struct solver_ctx *ctx = (struct solver_ctx *)vctx;
+    int i, j, lmin, gmax, nchanged = 0;
+    unsigned char *gns, *lns;
+    struct solver_link *link;
+
+    for (i = 0; i < ctx->nlinks; i++) {
+        link = &ctx->links[i];
+        solver_nminmax(solver, link->gx, link->gy, NULL, &gmax, &gns);
+        solver_nminmax(solver, link->lx, link->ly, &lmin, NULL, &lns);
+
+        for (j = 0; j < solver->o; j++) {
+            /* For the 'greater' end of the link, discount all numbers
+             * too small to satisfy the inequality. */
+            if (gns[j]) {
+                if (j < (lmin+link->len)) {
+#ifdef STANDALONE_SOLVER
+                    if (solver_show_working) {
+                        printf("%*slink elimination, (%d,%d) > (%d,%d):\n",
+                               solver_recurse_depth*4, "",
+                               link->gx+1, link->gy+1, link->lx+1, link->ly+1);
+                        printf("%*s  ruling out %d at (%d,%d)\n",
+                               solver_recurse_depth*4, "",
+                               j+1, link->gx+1, link->gy+1);
+                    }
+#endif
+                    cube(link->gx, link->gy, j+1) = FALSE;
+                    nchanged++;
+                }
+            }
+            /* For the 'lesser' end of the link, discount all numbers
+             * too large to satisfy inequality. */
+            if (lns[j]) {
+                if (j > (gmax-link->len)) {
+#ifdef STANDALONE_SOLVER
+                    if (solver_show_working) {
+                        printf("%*slink elimination, (%d,%d) > (%d,%d):\n",
+                               solver_recurse_depth*4, "",
+                               link->gx+1, link->gy+1, link->lx+1, link->ly+1);
+                        printf("%*s  ruling out %d at (%d,%d)\n",
+                               solver_recurse_depth*4, "",
+                               j+1, link->lx+1, link->ly+1);
+                    }
+#endif
+                    cube(link->lx, link->ly, j+1) = FALSE;
+                    nchanged++;
+                }
+            }
+        }
+    }
+    return nchanged;
+}
+
+static int solver_adjacent(struct latin_solver *solver, void *vctx)
+{
+    struct solver_ctx *ctx = (struct solver_ctx *)vctx;
+    int nchanged = 0, x, y, i, n, o = solver->o, nx, ny, gd;
+
+    /* Update possible values based on known values and adjacency clues. */
+
+    for (x = 0; x < o; x++) {
+        for (y = 0; y < o; y++) {
+            if (grid(x, y) == 0) continue;
+
+            /* We have a definite number here. Make sure that any
+             * adjacent possibles reflect the adjacent/non-adjacent clue. */
+
+            for (i = 0; i < 4; i++) {
+                int isadjacent = (GRID(ctx->state, flags, x, y) & adjthan[i].f);
+
+                nx = x + adjthan[i].dx, ny = y + adjthan[i].dy;
+                if (nx < 0 || ny < 0 || nx >= o || ny >= o)
+                    continue;
+
+                for (n = 0; n < o; n++) {
+                    /* Continue past numbers the adjacent square _could_ be,
+                     * given the clue we have. */
+                    gd = abs((n+1) - grid(x, y));
+                    if (isadjacent && (gd == 1)) continue;
+                    if (!isadjacent && (gd != 1)) continue;
+
+                    if (cube(nx, ny, n+1) == FALSE)
+                        continue; /* already discounted this possibility. */
+
+#ifdef STANDALONE_SOLVER
+                    if (solver_show_working) {
+                        printf("%*sadjacent elimination, (%d,%d):%d %s (%d,%d):\n",
+                               solver_recurse_depth*4, "",
+                               x+1, y+1, grid(x, y), isadjacent ? "|" : "!|", nx+1, ny+1);
+                        printf("%*s  ruling out %d at (%d,%d)\n",
+                               solver_recurse_depth*4, "", n+1, nx+1, ny+1);
+                    }
+#endif
+                    cube(nx, ny, n+1) = FALSE;
+                    nchanged++;
+                }
+            }
+        }
+    }
+
+    return nchanged;
+}
+
+static int solver_adjacent_set(struct latin_solver *solver, void *vctx)
+{
+    struct solver_ctx *ctx = (struct solver_ctx *)vctx;
+    int x, y, i, n, nn, o = solver->o, nx, ny, gd;
+    int nchanged = 0, *scratch = snewn(o, int);
+
+    /* Update possible values based on other possible values
+     * of adjacent squares, and adjacency clues. */
+
+    for (x = 0; x < o; x++) {
+        for (y = 0; y < o; y++) {
+            for (i = 0; i < 4; i++) {
+                int isadjacent = (GRID(ctx->state, flags, x, y) & adjthan[i].f);
+
+                nx = x + adjthan[i].dx, ny = y + adjthan[i].dy;
+                if (nx < 0 || ny < 0 || nx >= o || ny >= o)
+                    continue;
+
+                /* We know the current possibles for the square (x,y)
+                 * and also the adjacency clue from (x,y) to (nx,ny).
+                 * Construct a maximum set of possibles for (nx,ny)
+                 * in scratch, based on these constraints... */
+
+                memset(scratch, 0, o*sizeof(int));
+
+                for (n = 0; n < o; n++) {
+                    if (cube(x, y, n+1) == FALSE) continue;
+
+                    for (nn = 0; nn < o; nn++) {
+                        if (n == nn) continue;
+
+                        gd = abs(nn - n);
+                        if (isadjacent && (gd != 1)) continue;
+                        if (!isadjacent && (gd == 1)) continue;
+
+                        scratch[nn] = 1;
+                    }
+                }
+
+                /* ...and remove any possibilities for (nx,ny) that are
+                 * currently set but are not indicated in scratch. */
+                for (n = 0; n < o; n++) {
+                    if (scratch[n] == 1) continue;
+                    if (cube(nx, ny, n+1) == FALSE) continue;
+
+#ifdef STANDALONE_SOLVER
+                    if (solver_show_working) {
+                        printf("%*sadjacent possible elimination, (%d,%d) %s (%d,%d):\n",
+                               solver_recurse_depth*4, "",
+                               x+1, y+1, isadjacent ? "|" : "!|", nx+1, ny+1);
+                        printf("%*s  ruling out %d at (%d,%d)\n",
+                               solver_recurse_depth*4, "", n+1, nx+1, ny+1);
+                    }
+#endif
+                    cube(nx, ny, n+1) = FALSE;
+                    nchanged++;
+                }
+            }
+        }
+    }
+
+    return nchanged;
+}
+
+static int solver_easy(struct latin_solver *solver, void *vctx)
+{
+    struct solver_ctx *ctx = (struct solver_ctx *)vctx;
+    if (ctx->state->adjacent)
+        return solver_adjacent(solver, vctx);
+    else
+        return solver_links(solver, vctx);
+}
+
+static int solver_set(struct latin_solver *solver, void *vctx)
+{
+    struct solver_ctx *ctx = (struct solver_ctx *)vctx;
+    if (ctx->state->adjacent)
+        return solver_adjacent_set(solver, vctx);
+    else
+        return 0;
+}
+
+#define SOLVER(upper,title,func,lower) func,
+static usersolver_t const unequal_solvers[] = { DIFFLIST(SOLVER) };
+
+static int solver_state(game_state *state, int maxdiff)
+{
+    struct solver_ctx *ctx = new_ctx(state);
+    struct latin_solver solver;
+    int diff;
+
+    latin_solver_alloc(&solver, state->nums, state->order);
+
+    diff = latin_solver_main(&solver, maxdiff,
+                             DIFF_LATIN, DIFF_SET, DIFF_EXTREME,
+                             DIFF_EXTREME, DIFF_RECURSIVE,
+                             unequal_solvers, ctx, clone_ctx, free_ctx);
+
+    memcpy(state->hints, solver.cube, state->order*state->order*state->order);
+
+    free_ctx(ctx);
+
+    latin_solver_free(&solver);
+
+    if (diff == DIFF_IMPOSSIBLE)
+        return -1;
+    if (diff == DIFF_UNFINISHED)
+        return 0;
+    if (diff == DIFF_AMBIGUOUS)
+        return 2;
+    return 1;
+}
+
+static game_state *solver_hint(const game_state *state, int *diff_r,
+                               int mindiff, int maxdiff)
+{
+    game_state *ret = dup_game(state);
+    int diff, r = 0;
+
+    for (diff = mindiff; diff <= maxdiff; diff++) {
+        r = solver_state(ret, diff);
+        debug(("solver_state after %s %d", unequal_diffnames[diff], r));
+        if (r != 0) goto done;
+    }
+
+done:
+    if (diff_r) *diff_r = (r > 0) ? diff : -1;
+    return ret;
+}
+
+/* ----------------------------------------------------------
+ * Game generation.
+ */
+
+static char *latin_desc(digit *sq, size_t order)
+{
+    int o2 = order*order, i;
+    char *soln = snewn(o2+2, char);
+
+    soln[0] = 'S';
+    for (i = 0; i < o2; i++)
+        soln[i+1] = n2c(sq[i], order);
+    soln[o2+1] = '\0';
+
+    return soln;
+}
+
+/* returns non-zero if it placed (or could have placed) clue. */
+static int gg_place_clue(game_state *state, int ccode, digit *latin, int checkonly)
+{
+    int loc = ccode / 5, which = ccode % 5;
+    int x = loc % state->order, y = loc / state->order;
+
+    assert(loc < state->order*state->order);
+
+    if (which == 4) {           /* add number */
+        if (state->nums[loc] != 0) {
+#ifdef STANDALONE_SOLVER
+            if (state->nums[loc] != latin[loc]) {
+                printf("inconsistency for (%d,%d): state %d latin %d\n",
+                       x+1, y+1, state->nums[loc], latin[loc]);
+            }
+#endif
+            assert(state->nums[loc] == latin[loc]);
+            return 0;
+        }
+        if (!checkonly) {
+            state->nums[loc] = latin[loc];
+        }
+    } else {                    /* add flag */
+        int lx, ly, lloc;
+
+        if (state->adjacent)
+            return 0; /* never add flag clues in adjacent mode (they're always
+                         all present) */
+
+        if (state->flags[loc] & adjthan[which].f)
+            return 0; /* already has flag. */
+
+        lx = x + adjthan[which].dx;
+        ly = y + adjthan[which].dy;
+        if (lx < 0 || ly < 0 || lx >= state->order || ly >= state->order)
+            return 0; /* flag compares to off grid */
+
+        lloc = loc + adjthan[which].dx + adjthan[which].dy*state->order;
+        if (latin[loc] <= latin[lloc])
+            return 0; /* flag would be incorrect */
+
+        if (!checkonly) {
+            state->flags[loc] |= adjthan[which].f;
+        }
+    }
+    return 1;
+}
+
+/* returns non-zero if it removed (or could have removed) the clue. */
+static int gg_remove_clue(game_state *state, int ccode, int checkonly)
+{
+    int loc = ccode / 5, which = ccode % 5;
+#ifdef STANDALONE_SOLVER
+    int x = loc % state->order, y = loc / state->order;
+#endif
+
+    assert(loc < state->order*state->order);
+
+    if (which == 4) {           /* remove number. */
+        if (state->nums[loc] == 0) return 0;
+        if (!checkonly) {
+#ifdef STANDALONE_SOLVER
+            if (solver_show_working)
+                printf("gg_remove_clue: removing %d at (%d,%d)",
+                       state->nums[loc], x+1, y+1);
+#endif
+            state->nums[loc] = 0;
+        }
+    } else {                    /* remove flag */
+        if (state->adjacent)
+            return 0; /* never remove clues in adjacent mode. */
+
+        if (!(state->flags[loc] & adjthan[which].f)) return 0;
+        if (!checkonly) {
+#ifdef STANDALONE_SOLVER
+            if (solver_show_working)
+               printf("gg_remove_clue: removing %c at (%d,%d)",
+                       adjthan[which].c, x+1, y+1);
+#endif
+            state->flags[loc] &= ~adjthan[which].f;
+        }
+    }
+    return 1;
+}
+
+static int gg_best_clue(game_state *state, int *scratch, digit *latin)
+{
+    int ls = state->order * state->order * 5;
+    int maxposs = 0, minclues = 5, best = -1, i, j;
+    int nposs, nclues, loc;
+
+#ifdef STANDALONE_SOLVER
+    if (solver_show_working) {
+        game_debug(state);
+        latin_solver_debug(state->hints, state->order);
+    }
+#endif
+
+    for (i = ls; i-- > 0 ;) {
+        if (!gg_place_clue(state, scratch[i], latin, 1)) continue;
+
+        loc = scratch[i] / 5;
+        for (j = nposs = 0; j < state->order; j++) {
+            if (state->hints[loc*state->order + j]) nposs++;
+        }
+        for (j = nclues = 0; j < 4; j++) {
+            if (state->flags[loc] & adjthan[j].f) nclues++;
+        }
+        if ((nposs > maxposs) ||
+            (nposs == maxposs && nclues < minclues)) {
+            best = i; maxposs = nposs; minclues = nclues;
+#ifdef STANDALONE_SOLVER
+            if (solver_show_working) {
+                int x = loc % state->order, y = loc / state->order;
+                printf("gg_best_clue: b%d (%d,%d) new best [%d poss, %d clues].\n",
+                       best, x+1, y+1, nposs, nclues);
+            }
+#endif
+        }
+    }
+    /* if we didn't solve, we must have 1 clue to place! */
+    assert(best != -1);
+    return best;
+}
+
+#ifdef STANDALONE_SOLVER
+int maxtries;
+#define MAXTRIES maxtries
+#else
+#define MAXTRIES 50
+#endif
+int gg_solved;
+
+static int game_assemble(game_state *new, int *scratch, digit *latin,
+                         int difficulty)
+{
+    game_state *copy = dup_game(new);
+    int best;
+
+    if (difficulty >= DIFF_RECURSIVE) {
+        /* We mustn't use any solver that might guess answers;
+         * if it guesses wrongly but solves, gg_place_clue will
+         * get mighty confused. We will always trim clues down
+         * (making it more difficult) in game_strip, which doesn't
+         * have this problem. */
+        difficulty = DIFF_RECURSIVE-1;
+    }
+
+#ifdef STANDALONE_SOLVER
+    if (solver_show_working) {
+        game_debug(new);
+        latin_solver_debug(new->hints, new->order);
+    }
+#endif
+
+    while(1) {
+        gg_solved++;
+        if (solver_state(copy, difficulty) == 1) break;
+
+        best = gg_best_clue(copy, scratch, latin);
+        gg_place_clue(new, scratch[best], latin, 0);
+        gg_place_clue(copy, scratch[best], latin, 0);
+    }
+    free_game(copy);
+#ifdef STANDALONE_SOLVER
+    if (solver_show_working) {
+        char *dbg = game_text_format(new);
+        printf("game_assemble: done, %d solver iterations:\n%s\n", gg_solved, dbg);
+        sfree(dbg);
+    }
+#endif
+    return 0;
+}
+
+static void game_strip(game_state *new, int *scratch, digit *latin,
+                       int difficulty)
+{
+    int o = new->order, o2 = o*o, lscratch = o2*5, i;
+    game_state *copy = blank_game(new->order, new->adjacent);
+
+    /* For each symbol (if it exists in new), try and remove it and
+     * solve again; if we couldn't solve without it put it back. */
+    for (i = 0; i < lscratch; i++) {
+        if (!gg_remove_clue(new, scratch[i], 0)) continue;
+
+        memcpy(copy->nums,  new->nums,  o2 * sizeof(digit));
+        memcpy(copy->flags, new->flags, o2 * sizeof(unsigned int));
+        gg_solved++;
+        if (solver_state(copy, difficulty) != 1) {
+            /* put clue back, we can't solve without it. */
+            int ret = gg_place_clue(new, scratch[i], latin, 0);
+            assert(ret == 1);
+        } else {
+#ifdef STANDALONE_SOLVER
+            if (solver_show_working)
+                printf("game_strip: clue was redundant.");
+#endif
+        }
+    }
+    free_game(copy);
+#ifdef STANDALONE_SOLVER
+    if (solver_show_working) {
+        char *dbg = game_text_format(new);
+        debug(("game_strip: done, %d solver iterations.", gg_solved));
+        debug(("%s", dbg));
+        sfree(dbg);
+    }
+#endif
+}
+
+static void add_adjacent_flags(game_state *state, digit *latin)
+{
+    int x, y, o = state->order;
+
+    /* All clues in adjacent mode are always present (the only variables are
+     * the numbers). This adds all the flags to state based on the supplied
+     * latin square. */
+
+    for (y = 0; y < o; y++) {
+        for (x = 0; x < o; x++) {
+            if (x < (o-1) && (abs(latin[y*o+x] - latin[y*o+x+1]) == 1)) {
+                GRID(state, flags, x, y) |= F_ADJ_RIGHT;
+                GRID(state, flags, x+1, y) |= F_ADJ_LEFT;
+            }
+            if (y < (o-1) && (abs(latin[y*o+x] - latin[(y+1)*o+x]) == 1)) {
+                GRID(state, flags, x, y) |= F_ADJ_DOWN;
+                GRID(state, flags, x, y+1) |= F_ADJ_UP;
+            }
+        }
+    }
+}
+
+static char *new_game_desc(const game_params *params_in, random_state *rs,
+                           char **aux, int interactive)
+{
+    game_params params_copy = *params_in; /* structure copy */
+    game_params *params = &params_copy;
+    digit *sq = NULL;
+    int i, x, y, retlen, k, nsol;
+    int o2 = params->order * params->order, ntries = 1;
+    int *scratch, lscratch = o2*5;
+    char *ret, buf[80];
+    game_state *state = blank_game(params->order, params->adjacent);
+
+    /* Generate a list of 'things to strip' (randomised later) */
+    scratch = snewn(lscratch, int);
+    /* Put the numbers (4 mod 5) before the inequalities (0-3 mod 5) */
+    for (i = 0; i < lscratch; i++) scratch[i] = (i%o2)*5 + 4 - (i/o2);
+
+generate:
+#ifdef STANDALONE_SOLVER
+    if (solver_show_working)
+        printf("new_game_desc: generating %s puzzle, ntries so far %d\n",
+               unequal_diffnames[params->diff], ntries);
+#endif
+    if (sq) sfree(sq);
+    sq = latin_generate(params->order, rs);
+    latin_debug(sq, params->order);
+    /* Separately shuffle the numeric and inequality clues */
+    shuffle(scratch, lscratch/5, sizeof(int), rs);
+    shuffle(scratch+lscratch/5, 4*lscratch/5, sizeof(int), rs);
+
+    memset(state->nums, 0, o2 * sizeof(digit));
+    memset(state->flags, 0, o2 * sizeof(unsigned int));
+
+    if (state->adjacent) {
+        /* All adjacency flags are always present. */
+        add_adjacent_flags(state, sq);
+    }
+
+    gg_solved = 0;
+    if (game_assemble(state, scratch, sq, params->diff) < 0)
+        goto generate;
+    game_strip(state, scratch, sq, params->diff);
+
+    if (params->diff > 0) {
+        game_state *copy = dup_game(state);
+        nsol = solver_state(copy, params->diff-1);
+        free_game(copy);
+        if (nsol > 0) {
+#ifdef STANDALONE_SOLVER
+            if (solver_show_working)
+                printf("game_assemble: puzzle as generated is too easy.\n");
+#endif
+            if (ntries < MAXTRIES) {
+                ntries++;
+                goto generate;
+            }
+#ifdef STANDALONE_SOLVER
+            if (solver_show_working)
+                printf("Unable to generate %s %dx%d after %d attempts.\n",
+                       unequal_diffnames[params->diff],
+                       params->order, params->order, MAXTRIES);
+#endif
+            params->diff--;
+        }
+    }
+#ifdef STANDALONE_SOLVER
+    if (solver_show_working)
+        printf("new_game_desc: generated %s puzzle; %d attempts (%d solver).\n",
+               unequal_diffnames[params->diff], ntries, gg_solved);
+#endif
+
+    ret = NULL; retlen = 0;
+    for (y = 0; y < params->order; y++) {
+        for (x = 0; x < params->order; x++) {
+            unsigned int f = GRID(state, flags, x, y);
+            k = sprintf(buf, "%d%s%s%s%s,",
+                        GRID(state, nums, x, y),
+                        (f & F_ADJ_UP)    ? "U" : "",
+                        (f & F_ADJ_RIGHT) ? "R" : "",
+                        (f & F_ADJ_DOWN)  ? "D" : "",
+                        (f & F_ADJ_LEFT)  ? "L" : "");
+
+            ret = sresize(ret, retlen + k + 1, char);
+            strcpy(ret + retlen, buf);
+            retlen += k;
+        }
+    }
+    *aux = latin_desc(sq, params->order);
+
+    free_game(state);
+    sfree(sq);
+    sfree(scratch);
+
+    return ret;
+}
+
+static game_state *load_game(const game_params *params, const char *desc,
+                             char **why_r)
+{
+    game_state *state = blank_game(params->order, params->adjacent);
+    const char *p = desc;
+    int i = 0, n, o = params->order, x, y;
+    char *why = NULL;
+
+    while (*p) {
+        while (*p >= 'a' && *p <= 'z') {
+            i += *p - 'a' + 1;
+            p++;
+        }
+        if (i >= o*o) {
+            why = "Too much data to fill grid"; goto fail;
+        }
+
+        if (*p < '0' || *p > '9') {
+            why = "Expecting number in game description"; goto fail;
+        }
+        n = atoi(p);
+        if (n < 0 || n > o) {
+            why = "Out-of-range number in game description"; goto fail;
+        }
+        state->nums[i] = (digit)n;
+        while (*p >= '0' && *p <= '9') p++; /* skip number */
+
+        if (state->nums[i] != 0)
+            state->flags[i] |= F_IMMUTABLE; /* === number set by game description */
+
+        while (*p == 'U' || *p == 'R' || *p == 'D' || *p == 'L') {
+            switch (*p) {
+            case 'U': state->flags[i] |= F_ADJ_UP;    break;
+            case 'R': state->flags[i] |= F_ADJ_RIGHT; break;
+            case 'D': state->flags[i] |= F_ADJ_DOWN;  break;
+            case 'L': state->flags[i] |= F_ADJ_LEFT;  break;
+            default: why = "Expecting flag URDL in game description"; goto fail;
+            }
+            p++;
+        }
+        i++;
+        if (i < o*o && *p != ',') {
+            why = "Missing separator"; goto fail;
+        }
+        if (*p == ',') p++;
+    }
+    if (i < o*o) {
+        why = "Not enough data to fill grid"; goto fail;
+    }
+    i = 0;
+    for (y = 0; y < o; y++) {
+        for (x = 0; x < o; x++) {
+            for (n = 0; n < 4; n++) {
+                if (GRID(state, flags, x, y) & adjthan[n].f) {
+                    int nx = x + adjthan[n].dx;
+                    int ny = y + adjthan[n].dy;
+                    /* a flag must not point us off the grid. */
+                    if (nx < 0 || ny < 0 || nx >= o || ny >= o) {
+                        why = "Flags go off grid"; goto fail;
+                    }
+                    if (params->adjacent) {
+                        /* if one cell is adjacent to another, the other must
+                         * also be adjacent to the first. */
+                        if (!(GRID(state, flags, nx, ny) & adjthan[n].fo)) {
+                            why = "Flags contradicting each other"; goto fail;
+                        }
+                    } else {
+                        /* if one cell is GT another, the other must _not_ also
+                         * be GT the first. */
+                        if (GRID(state, flags, nx, ny) & adjthan[n].fo) {
+                            why = "Flags contradicting each other"; goto fail;
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    return state;
+
+fail:
+    free_game(state);
+    if (why_r) *why_r = why;
+    return NULL;
+}
+
+static game_state *new_game(midend *me, const game_params *params,
+                            const char *desc)
+{
+    game_state *state = load_game(params, desc, NULL);
+    if (!state) {
+        assert("Unable to load ?validated game.");
+        return NULL;
+    }
+    return state;
+}
+
+static char *validate_desc(const game_params *params, const char *desc)
+{
+    char *why = NULL;
+    game_state *dummy = load_game(params, desc, &why);
+    if (dummy) {
+        free_game(dummy);
+        assert(!why);
+    } else
+        assert(why);
+    return why;
+}
+
+static char *solve_game(const game_state *state, const game_state *currstate,
+                        const char *aux, char **error)
+{
+    game_state *solved;
+    int r;
+    char *ret = NULL;
+
+    if (aux) return dupstr(aux);
+
+    solved = dup_game(state);
+    for (r = 0; r < state->order*state->order; r++) {
+        if (!(solved->flags[r] & F_IMMUTABLE))
+            solved->nums[r] = 0;
+    }
+    r = solver_state(solved, DIFFCOUNT-1);   /* always use full solver */
+    if (r > 0) ret = latin_desc(solved->nums, solved->order);
+    free_game(solved);
+    return ret;
+}
+
+/* ----------------------------------------------------------
+ * Game UI input processing.
+ */
+
+struct game_ui {
+    int hx, hy;                         /* as for solo.c, highlight pos */
+    int hshow, hpencil, hcursor;        /* show state, type, and ?cursor. */
+};
+
+static game_ui *new_ui(const game_state *state)
+{
+    game_ui *ui = snew(game_ui);
+
+    ui->hx = ui->hy = 0;
+    ui->hpencil = ui->hshow = ui->hcursor = 0;
+
+    return ui;
+}
+
+static void free_ui(game_ui *ui)
+{
+    sfree(ui);
+}
+
+static char *encode_ui(const game_ui *ui)
+{
+    return NULL;
+}
+
+static void decode_ui(game_ui *ui, const char *encoding)
+{
+}
+
+static void game_changed_state(game_ui *ui, const game_state *oldstate,
+                               const game_state *newstate)
+{
+    /* See solo.c; if we were pencil-mode highlighting and
+     * somehow a square has just been properly filled, cancel
+     * pencil mode. */
+    if (ui->hshow && ui->hpencil && !ui->hcursor &&
+        GRID(newstate, nums, ui->hx, ui->hy) != 0) {
+        ui->hshow = 0;
+    }
+}
+
+struct game_drawstate {
+    int tilesize, order, started, adjacent;
+    digit *nums;                /* copy of nums, o^2 */
+    unsigned char *hints;       /* copy of hints, o^3 */
+    unsigned int *flags;        /* o^2 */
+
+    int hx, hy, hshow, hpencil; /* as for game_ui. */
+    int hflash;
+};
+
+static char *interpret_move(const game_state *state, game_ui *ui,
+                            const game_drawstate *ds,
+                            int ox, int oy, int button)
+{
+    int x = FROMCOORD(ox), y = FROMCOORD(oy), n;
+    char buf[80];
+    int shift_or_control = button & (MOD_SHFT | MOD_CTRL);
+
+    button &= ~MOD_MASK;
+
+    if (x >= 0 && x < ds->order && y >= 0 && y < ds->order && IS_MOUSE_DOWN(button)) {
+        if (oy - COORD(y) > TILE_SIZE && ox - COORD(x) > TILE_SIZE)
+            return NULL;
+
+        if (oy - COORD(y) > TILE_SIZE) {
+            if (GRID(state, flags, x, y) & F_ADJ_DOWN)
+                sprintf(buf, "F%d,%d,%d", x, y, F_SPENT_DOWN);
+            else if (y + 1 < ds->order && GRID(state, flags, x, y + 1) & F_ADJ_UP)
+                sprintf(buf, "F%d,%d,%d", x, y + 1, F_SPENT_UP);
+            else return NULL;
+            return dupstr(buf);
+        }
+
+        if (ox - COORD(x) > TILE_SIZE) {
+            if (GRID(state, flags, x, y) & F_ADJ_RIGHT)
+                sprintf(buf, "F%d,%d,%d", x, y, F_SPENT_RIGHT);
+            else if (x + 1 < ds->order && GRID(state, flags, x + 1, y) & F_ADJ_LEFT)
+                sprintf(buf, "F%d,%d,%d", x + 1, y, F_SPENT_LEFT);
+            else return NULL;
+            return dupstr(buf);
+        }
+
+        if (button == LEFT_BUTTON) {
+            /* normal highlighting for non-immutable squares */
+            if (GRID(state, flags, x, y) & F_IMMUTABLE)
+                ui->hshow = 0;
+            else if (x == ui->hx && y == ui->hy &&
+                     ui->hshow && ui->hpencil == 0)
+                ui->hshow = 0;
+            else {
+                ui->hx = x; ui->hy = y; ui->hpencil = 0;
+                ui->hshow = 1;
+            }
+            ui->hcursor = 0;
+            return "";
+        }
+        if (button == RIGHT_BUTTON) {
+            /* pencil highlighting for non-filled squares */
+            if (GRID(state, nums, x, y) != 0)
+                ui->hshow = 0;
+            else if (x == ui->hx && y == ui->hy &&
+                     ui->hshow && ui->hpencil)
+                ui->hshow = 0;
+            else {
+                ui->hx = x; ui->hy = y; ui->hpencil = 1;
+                ui->hshow = 1;
+            }
+            ui->hcursor = 0;
+            return "";
+        }
+    }
+
+    if (IS_CURSOR_MOVE(button)) {
+        if (shift_or_control) {
+            int nx = ui->hx, ny = ui->hy, i, self;
+            move_cursor(button, &nx, &ny, ds->order, ds->order, FALSE);
+            ui->hshow = ui->hcursor = 1;
+
+            for (i = 0; i < 4 && (nx != ui->hx + adjthan[i].dx ||
+                                  ny != ui->hy + adjthan[i].dy); ++i);
+
+            if (i == 4)
+                return ""; /* invalid direction, i.e. out of the board */
+
+            if (!(GRID(state, flags, ui->hx, ui->hy) & adjthan[i].f ||
+                  GRID(state, flags, nx,     ny    ) & adjthan[i].fo))
+                return ""; /* no clue to toggle */
+
+            if (state->adjacent)
+                self = (adjthan[i].dx >= 0 && adjthan[i].dy >= 0);
+            else
+                self = (GRID(state, flags, ui->hx, ui->hy) & adjthan[i].f);
+
+            if (self)
+                sprintf(buf, "F%d,%d,%d", ui->hx, ui->hy,
+                        ADJ_TO_SPENT(adjthan[i].f));
+            else
+                sprintf(buf, "F%d,%d,%d", nx, ny,
+                        ADJ_TO_SPENT(adjthan[i].fo));
+
+            return dupstr(buf);
+        } else {
+            move_cursor(button, &ui->hx, &ui->hy, ds->order, ds->order, FALSE);
+            ui->hshow = ui->hcursor = 1;
+            return "";
+        }
+    }
+    if (ui->hshow && IS_CURSOR_SELECT(button)) {
+        ui->hpencil = 1 - ui->hpencil;
+        ui->hcursor = 1;
+        return "";
+    }
+
+    n = c2n(button, state->order);
+    if (ui->hshow && n >= 0 && n <= ds->order) {
+        debug(("button %d, cbutton %d", button, (int)((char)button)));
+
+        debug(("n %d, h (%d,%d) p %d flags 0x%x nums %d",
+               n, ui->hx, ui->hy, ui->hpencil,
+               GRID(state, flags, ui->hx, ui->hy),
+               GRID(state, nums, ui->hx, ui->hy)));
+
+        if (GRID(state, flags, ui->hx, ui->hy) & F_IMMUTABLE)
+            return NULL;        /* can't edit immutable square (!) */
+        if (ui->hpencil && GRID(state, nums, ui->hx, ui->hy) > 0)
+            return NULL;        /* can't change hints on filled square (!) */
+
+
+        sprintf(buf, "%c%d,%d,%d",
+                (char)(ui->hpencil && n > 0 ? 'P' : 'R'), ui->hx, ui->hy, n);
+
+        if (!ui->hcursor) ui->hshow = 0;
+
+        return dupstr(buf);
+    }
+
+    if (button == 'H' || button == 'h')
+        return dupstr("H");
+    if (button == 'M' || button == 'm')
+        return dupstr("M");
+
+    return NULL;
+}
+
+static game_state *execute_move(const game_state *state, const char *move)
+{
+    game_state *ret = NULL;
+    int x, y, n, i, rc;
+
+    debug(("execute_move: %s", move));
+
+    if ((move[0] == 'P' || move[0] == 'R') &&
+        sscanf(move+1, "%d,%d,%d", &x, &y, &n) == 3 &&
+        x >= 0 && x < state->order && y >= 0 && y < state->order &&
+        n >= 0 && n <= state->order) {
+        ret = dup_game(state);
+        if (move[0] == 'P' && n > 0)
+            HINT(ret, x, y, n-1) = !HINT(ret, x, y, n-1);
+        else {
+            GRID(ret, nums, x, y) = n;
+            for (i = 0; i < state->order; i++)
+                HINT(ret, x, y, i) = 0;
+
+            /* real change to grid; check for completion */
+            if (!ret->completed && check_complete(ret->nums, ret, 1) > 0)
+                ret->completed = TRUE;
+        }
+        return ret;
+    } else if (move[0] == 'S') {
+        const char *p;
+
+        ret = dup_game(state);
+        ret->completed = ret->cheated = TRUE;
+
+        p = move+1;
+        for (i = 0; i < state->order*state->order; i++) {
+            n = c2n((int)*p, state->order);
+            if (!*p || n <= 0 || n > state->order)
+                goto badmove;
+            ret->nums[i] = n;
+            p++;
+        }
+        if (*p) goto badmove;
+        rc = check_complete(ret->nums, ret, 1);
+        assert(rc > 0);
+        return ret;
+    } else if (move[0] == 'M') {
+        ret = dup_game(state);
+        for (x = 0; x < state->order; x++) {
+            for (y = 0; y < state->order; y++) {
+                for (n = 0; n < state->order; n++) {
+                    HINT(ret, x, y, n) = 1;
+                }
+            }
+        }
+        return ret;
+    } else if (move[0] == 'H') {
+        return solver_hint(state, NULL, DIFF_EASY, DIFF_EASY);
+    } else if (move[0] == 'F' && sscanf(move+1, "%d,%d,%d", &x, &y, &n) == 3 &&
+               x >= 0 && x < state->order && y >= 0 && y < state->order) {
+        ret = dup_game(state);
+        GRID(ret, flags, x, y) ^= n;
+        return ret;
+    }
+
+badmove:
+    if (ret) free_game(ret);
+    return NULL;
+}
+
+/* ----------------------------------------------------------------------
+ * Drawing/printing routines.
+ */
+
+#define DRAW_SIZE (TILE_SIZE*ds->order + GAP_SIZE*(ds->order-1) + BORDER*2)
+
+static void game_compute_size(const game_params *params, int tilesize,
+                              int *x, int *y)
+{
+    /* Ick: fake up `ds->tilesize' for macro expansion purposes */
+    struct { int tilesize, order; } ads, *ds = &ads;
+    ads.tilesize = tilesize;
+    ads.order = params->order;
+
+    *x = *y = DRAW_SIZE;
+}
+
+static void game_set_size(drawing *dr, game_drawstate *ds,
+                          const game_params *params, int tilesize)
+{
+    ds->tilesize = tilesize;
+}
+
+static float *game_colours(frontend *fe, int *ncolours)
+{
+    float *ret = snewn(3 * NCOLOURS, float);
+    int i;
+
+    game_mkhighlight(fe, ret, COL_BACKGROUND, COL_HIGHLIGHT, COL_LOWLIGHT);
+
+    for (i = 0; i < 3; i++) {
+        ret[COL_TEXT * 3 + i] = 0.0F;
+        ret[COL_GRID * 3 + i] = 0.5F;
+    }
+
+    /* Lots of these were taken from solo.c. */
+    ret[COL_GUESS * 3 + 0] = 0.0F;
+    ret[COL_GUESS * 3 + 1] = 0.6F * ret[COL_BACKGROUND * 3 + 1];
+    ret[COL_GUESS * 3 + 2] = 0.0F;
+
+    ret[COL_ERROR * 3 + 0] = 1.0F;
+    ret[COL_ERROR * 3 + 1] = 0.0F;
+    ret[COL_ERROR * 3 + 2] = 0.0F;
+
+    ret[COL_PENCIL * 3 + 0] = 0.5F * ret[COL_BACKGROUND * 3 + 0];
+    ret[COL_PENCIL * 3 + 1] = 0.5F * ret[COL_BACKGROUND * 3 + 1];
+    ret[COL_PENCIL * 3 + 2] = ret[COL_BACKGROUND * 3 + 2];
+
+    *ncolours = NCOLOURS;
+    return ret;
+}
+
+static game_drawstate *game_new_drawstate(drawing *dr, const game_state *state)
+{
+    struct game_drawstate *ds = snew(struct game_drawstate);
+    int o2 = state->order*state->order, o3 = o2*state->order;
+
+    ds->tilesize = 0;
+    ds->order = state->order;
+    ds->adjacent = state->adjacent;
+
+    ds->nums = snewn(o2, digit);
+    ds->hints = snewn(o3, unsigned char);
+    ds->flags = snewn(o2, unsigned int);
+    memset(ds->nums, 0, o2*sizeof(digit));
+    memset(ds->hints, 0, o3);
+    memset(ds->flags, 0, o2*sizeof(unsigned int));
+
+    ds->hx = ds->hy = 0;
+    ds->started = ds->hshow = ds->hpencil = ds->hflash = 0;
+
+    return ds;
+}
+
+static void game_free_drawstate(drawing *dr, game_drawstate *ds)
+{
+    sfree(ds->nums);
+    sfree(ds->hints);
+    sfree(ds->flags);
+    sfree(ds);
+}
+
+static void draw_gt(drawing *dr, int ox, int oy,
+                    int dx1, int dy1, int dx2, int dy2, int col)
+{
+    int coords[12];
+    int xdx = (dx1+dx2 ? 0 : 1), xdy = (dx1+dx2 ? 1 : 0);
+    coords[0] = ox + xdx;
+    coords[1] = oy + xdy;
+    coords[2] = ox + xdx + dx1;
+    coords[3] = oy + xdy + dy1;
+    coords[4] = ox + xdx + dx1 + dx2;
+    coords[5] = oy + xdy + dy1 + dy2;
+    coords[6] = ox - xdx + dx1 + dx2;
+    coords[7] = oy - xdy + dy1 + dy2;
+    coords[8] = ox - xdx + dx1;
+    coords[9] = oy - xdy + dy1;
+    coords[10] = ox - xdx;
+    coords[11] = oy - xdy;
+    draw_polygon(dr, coords, 6, col, col);
+}
+
+#define COLOUR(direction) (f & (F_ERROR_##direction) ? COL_ERROR : \
+                           f & (F_SPENT_##direction) ? COL_SPENT : fg)
+
+static void draw_gts(drawing *dr, game_drawstate *ds, int ox, int oy,
+                     unsigned int f, int bg, int fg)
+{
+    int g = GAP_SIZE, g2 = (g+1)/2, g4 = (g+1)/4;
+
+    /* Draw all the greater-than signs emanating from this tile. */
+
+    if (f & F_ADJ_UP) {
+        if (bg >= 0) draw_rect(dr, ox, oy - g, TILE_SIZE, g, bg);
+        draw_gt(dr, ox+g2, oy-g4, g2, -g2, g2, g2, COLOUR(UP));
+        draw_update(dr, ox, oy-g, TILE_SIZE, g);
+    }
+    if (f & F_ADJ_RIGHT) {
+        if (bg >= 0) draw_rect(dr, ox + TILE_SIZE, oy, g, TILE_SIZE, bg);
+        draw_gt(dr, ox+TILE_SIZE+g4, oy+g2, g2, g2, -g2, g2, COLOUR(RIGHT));
+        draw_update(dr, ox+TILE_SIZE, oy, g, TILE_SIZE);
+    }
+    if (f & F_ADJ_DOWN) {
+        if (bg >= 0) draw_rect(dr, ox, oy + TILE_SIZE, TILE_SIZE, g, bg);
+        draw_gt(dr, ox+g2, oy+TILE_SIZE+g4, g2, g2, g2, -g2, COLOUR(DOWN));
+        draw_update(dr, ox, oy+TILE_SIZE, TILE_SIZE, g);
+    }
+    if (f & F_ADJ_LEFT) {
+        if (bg >= 0) draw_rect(dr, ox - g, oy, g, TILE_SIZE, bg);
+        draw_gt(dr, ox-g4, oy+g2, -g2, g2, g2, g2, COLOUR(LEFT));
+        draw_update(dr, ox-g, oy, g, TILE_SIZE);
+    }
+}
+
+static void draw_adjs(drawing *dr, game_drawstate *ds, int ox, int oy,
+                      unsigned int f, int bg, int fg)
+{
+    int g = GAP_SIZE, g38 = 3*(g+1)/8, g4 = (g+1)/4;
+
+    /* Draw all the adjacency bars relevant to this tile; we only have
+     * to worry about F_ADJ_RIGHT and F_ADJ_DOWN.
+     *
+     * If we _only_ have the error flag set (i.e. it's not supposed to be
+     * adjacent, but adjacent numbers were entered) draw an outline red bar.
+     */
+
+    if (f & (F_ADJ_RIGHT|F_ERROR_RIGHT)) {
+        if (f & F_ADJ_RIGHT) {
+            draw_rect(dr, ox+TILE_SIZE+g38, oy, g4, TILE_SIZE, COLOUR(RIGHT));
+        } else {
+            draw_rect_outline(dr, ox+TILE_SIZE+g38, oy, g4, TILE_SIZE, COL_ERROR);
+        }
+    } else if (bg >= 0) {
+        draw_rect(dr, ox+TILE_SIZE+g38, oy, g4, TILE_SIZE, bg);
+    }
+    draw_update(dr, ox+TILE_SIZE, oy, g, TILE_SIZE);
+
+    if (f & (F_ADJ_DOWN|F_ERROR_DOWN)) {
+        if (f & F_ADJ_DOWN) {
+            draw_rect(dr, ox, oy+TILE_SIZE+g38, TILE_SIZE, g4, COLOUR(DOWN));
+        } else {
+            draw_rect_outline(dr, ox, oy+TILE_SIZE+g38, TILE_SIZE, g4, COL_ERROR);
+        }
+    } else if (bg >= 0) {
+        draw_rect(dr, ox, oy+TILE_SIZE+g38, TILE_SIZE, g4, bg);
+    }
+    draw_update(dr, ox, oy+TILE_SIZE, TILE_SIZE, g);
+}
+
+static void draw_furniture(drawing *dr, game_drawstate *ds,
+                           const game_state *state, const game_ui *ui,
+                           int x, int y, int hflash)
+{
+    int ox = COORD(x), oy = COORD(y), bg, hon;
+    unsigned int f = GRID(state, flags, x, y);
+
+    bg = hflash ? COL_HIGHLIGHT : COL_BACKGROUND;
+
+    hon = (ui->hshow && x == ui->hx && y == ui->hy);
+
+    /* Clear square. */
+    draw_rect(dr, ox, oy, TILE_SIZE, TILE_SIZE,
+              (hon && !ui->hpencil) ? COL_HIGHLIGHT : bg);
+
+    /* Draw the highlight (pencil or full), if we're the highlight */
+    if (hon && ui->hpencil) {
+        int coords[6];
+        coords[0] = ox;
+        coords[1] = oy;
+        coords[2] = ox + TILE_SIZE/2;
+        coords[3] = oy;
+        coords[4] = ox;
+        coords[5] = oy + TILE_SIZE/2;
+        draw_polygon(dr, coords, 3, COL_HIGHLIGHT, COL_HIGHLIGHT);
+    }
+
+    /* Draw the square outline (which is the cursor, if we're the cursor). */
+    draw_rect_outline(dr, ox, oy, TILE_SIZE, TILE_SIZE, COL_GRID);
+
+    draw_update(dr, ox, oy, TILE_SIZE, TILE_SIZE);
+
+    /* Draw the adjacent clue signs. */
+    if (ds->adjacent)
+        draw_adjs(dr, ds, ox, oy, f, COL_BACKGROUND, COL_GRID);
+    else
+        draw_gts(dr, ds, ox, oy, f, COL_BACKGROUND, COL_TEXT);
+}
+
+static void draw_num(drawing *dr, game_drawstate *ds, int x, int y)
+{
+    int ox = COORD(x), oy = COORD(y);
+    unsigned int f = GRID(ds,flags,x,y);
+    char str[2];
+
+    /* (can assume square has just been cleared) */
+
+    /* Draw number, choosing appropriate colour */
+    str[0] = n2c(GRID(ds, nums, x, y), ds->order);
+    str[1] = '\0';
+    draw_text(dr, ox + TILE_SIZE/2, oy + TILE_SIZE/2,
+              FONT_VARIABLE, 3*TILE_SIZE/4, ALIGN_VCENTRE | ALIGN_HCENTRE,
+              (f & F_IMMUTABLE) ? COL_TEXT : (f & F_ERROR) ? COL_ERROR : COL_GUESS, str);
+}
+
+static void draw_hints(drawing *dr, game_drawstate *ds, int x, int y)
+{
+    int ox = COORD(x), oy = COORD(y);
+    int nhints, i, j, hw, hh, hmax, fontsz;
+    char str[2];
+
+    /* (can assume square has just been cleared) */
+
+    /* Draw hints; steal ingenious algorithm (basically)
+     * from solo.c:draw_number() */
+    for (i = nhints = 0; i < ds->order; i++) {
+        if (HINT(ds, x, y, i)) nhints++;
+    }
+
+    for (hw = 1; hw * hw < nhints; hw++);
+    if (hw < 3) hw = 3;
+    hh = (nhints + hw - 1) / hw;
+    if (hh < 2) hh = 2;
+    hmax = max(hw, hh);
+    fontsz = TILE_SIZE/(hmax*(11-hmax)/8);
+
+    for (i = j = 0; i < ds->order; i++) {
+        if (HINT(ds,x,y,i)) {
+            int hx = j % hw, hy = j / hw;
+
+            str[0] = n2c(i+1, ds->order);
+            str[1] = '\0';
+            draw_text(dr,
+                      ox + (4*hx+3) * TILE_SIZE / (4*hw+2),
+                      oy + (4*hy+3) * TILE_SIZE / (4*hh+2),
+                      FONT_VARIABLE, fontsz,
+                      ALIGN_VCENTRE | ALIGN_HCENTRE, COL_PENCIL, str);
+            j++;
+        }
+    }
+}
+
+static void game_redraw(drawing *dr, game_drawstate *ds,
+                        const game_state *oldstate, const game_state *state,
+                        int dir, const game_ui *ui,
+                        float animtime, float flashtime)
+{
+    int x, y, i, hchanged = 0, stale, hflash = 0;
+
+    debug(("highlight old (%d,%d), new (%d,%d)", ds->hx, ds->hy, ui->hx, ui->hy));
+
+    if (flashtime > 0 &&
+        (flashtime <= FLASH_TIME/3 || flashtime >= FLASH_TIME*2/3))
+         hflash = 1;
+
+    if (!ds->started) {
+        draw_rect(dr, 0, 0, DRAW_SIZE, DRAW_SIZE, COL_BACKGROUND);
+        draw_update(dr, 0, 0, DRAW_SIZE, DRAW_SIZE);
+    }
+    if (ds->hx != ui->hx || ds->hy != ui->hy ||
+        ds->hshow != ui->hshow || ds->hpencil != ui->hpencil)
+        hchanged = 1;
+
+    for (x = 0; x < ds->order; x++) {
+        for (y = 0; y < ds->order; y++) {
+            if (!ds->started)
+                stale = 1;
+            else if (hflash != ds->hflash)
+                stale = 1;
+            else
+                stale = 0;
+
+            if (hchanged) {
+                if ((x == ui->hx && y == ui->hy) ||
+                    (x == ds->hx && y == ds->hy))
+                    stale = 1;
+            }
+
+            if (GRID(state, nums, x, y) != GRID(ds, nums, x, y)) {
+                GRID(ds, nums, x, y) = GRID(state, nums, x, y);
+                stale = 1;
+            }
+            if (GRID(state, flags, x, y) != GRID(ds, flags, x, y)) {
+                GRID(ds, flags, x, y) = GRID(state, flags, x, y);
+                stale = 1;
+            }
+            if (GRID(ds, nums, x, y) == 0) {
+                /* We're not a number square (therefore we might
+                 * display hints); do we need to update? */
+                for (i = 0; i < ds->order; i++) {
+                    if (HINT(state, x, y, i) != HINT(ds, x, y, i)) {
+                        HINT(ds, x, y, i) = HINT(state, x, y, i);
+                        stale = 1;
+                    }
+                }
+            }
+            if (stale) {
+                draw_furniture(dr, ds, state, ui, x, y, hflash);
+                if (GRID(ds, nums, x, y) > 0)
+                    draw_num(dr, ds, x, y);
+                else
+                    draw_hints(dr, ds, x, y);
+            }
+        }
+    }
+    ds->hx = ui->hx; ds->hy = ui->hy;
+    ds->hshow = ui->hshow;
+    ds->hpencil = ui->hpencil;
+
+    ds->started = 1;
+    ds->hflash = hflash;
+}
+
+static float game_anim_length(const game_state *oldstate,
+                              const game_state *newstate, int dir, game_ui *ui)
+{
+    return 0.0F;
+}
+
+static float game_flash_length(const game_state *oldstate,
+                               const game_state *newstate, int dir, game_ui *ui)
+{
+    if (!oldstate->completed && newstate->completed &&
+        !oldstate->cheated && !newstate->cheated)
+        return FLASH_TIME;
+    return 0.0F;
+}
+
+static int game_status(const game_state *state)
+{
+    return state->completed ? +1 : 0;
+}
+
+static int game_timing_state(const game_state *state, game_ui *ui)
+{
+    return TRUE;
+}
+
+static void game_print_size(const game_params *params, float *x, float *y)
+{
+    int pw, ph;
+
+    /* 10mm squares by default, roughly the same as Grauniad. */
+    game_compute_size(params, 1000, &pw, &ph);
+    *x = pw / 100.0F;
+    *y = ph / 100.0F;
+}
+
+static void game_print(drawing *dr, const game_state *state, int tilesize)
+{
+    int ink = print_mono_colour(dr, 0);
+    int x, y, o = state->order, ox, oy, n;
+    char str[2];
+
+    /* Ick: fake up `ds->tilesize' for macro expansion purposes */
+    game_drawstate ads, *ds = &ads;
+    game_set_size(dr, ds, NULL, tilesize);
+
+    print_line_width(dr, 2 * TILE_SIZE / 40);
+
+    /* Squares, numbers, gt signs */
+    for (y = 0; y < o; y++) {
+        for (x = 0; x < o; x++) {
+            ox = COORD(x); oy = COORD(y);
+            n = GRID(state, nums, x, y);
+
+            draw_rect_outline(dr, ox, oy, TILE_SIZE, TILE_SIZE, ink);
+
+            str[0] = n ? n2c(n, state->order) : ' ';
+            str[1] = '\0';
+            draw_text(dr, ox + TILE_SIZE/2, oy + TILE_SIZE/2,
+                      FONT_VARIABLE, TILE_SIZE/2, ALIGN_VCENTRE | ALIGN_HCENTRE,
+                      ink, str);
+
+            if (state->adjacent)
+                draw_adjs(dr, ds, ox, oy, GRID(state, flags, x, y), -1, ink);
+            else
+                draw_gts(dr, ds, ox, oy, GRID(state, flags, x, y), -1, ink);
+        }
+    }
+}
+
+/* ----------------------------------------------------------------------
+ * Housekeeping.
+ */
+
+#ifdef COMBINED
+#define thegame unequal
+#endif
+
+const struct game thegame = {
+    "Unequal", "games.unequal", "unequal",
+    default_params,
+    game_fetch_preset, NULL,
+    decode_params,
+    encode_params,
+    free_params,
+    dup_params,
+    TRUE, game_configure, custom_params,
+    validate_params,
+    new_game_desc,
+    validate_desc,
+    new_game,
+    dup_game,
+    free_game,
+    TRUE, solve_game,
+    TRUE, game_can_format_as_text_now, game_text_format,
+    new_ui,
+    free_ui,
+    encode_ui,
+    decode_ui,
+    game_changed_state,
+    interpret_move,
+    execute_move,
+    PREFERRED_TILE_SIZE, game_compute_size, game_set_size,
+    game_colours,
+    game_new_drawstate,
+    game_free_drawstate,
+    game_redraw,
+    game_anim_length,
+    game_flash_length,
+    game_status,
+    TRUE, FALSE, game_print_size, game_print,
+    FALSE,                             /* wants_statusbar */
+    FALSE, game_timing_state,
+    REQUIRE_RBUTTON | REQUIRE_NUMPAD,  /* flags */
+};
+
+/* ----------------------------------------------------------------------
+ * Standalone solver.
+ */
+
+#ifdef STANDALONE_SOLVER
+
+#include <time.h>
+#include <stdarg.h>
+
+const char *quis = NULL;
+
+#if 0 /* currently unused */
+
+static void debug_printf(char *fmt, ...)
+{
+    char buf[4096];
+    va_list ap;
+
+    va_start(ap, fmt);
+    vsprintf(buf, fmt, ap);
+    puts(buf);
+    va_end(ap);
+}
+
+static void game_printf(game_state *state)
+{
+    char *dbg = game_text_format(state);
+    printf("%s", dbg);
+    sfree(dbg);
+}
+
+static void game_printf_wide(game_state *state)
+{
+    int x, y, i, n;
+
+    for (y = 0; y < state->order; y++) {
+        for (x = 0; x < state->order; x++) {
+            n = GRID(state, nums, x, y);
+            for (i = 0; i < state->order; i++) {
+                if (n > 0)
+                    printf("%c", n2c(n, state->order));
+                else if (HINT(state, x, y, i))
+                    printf("%c", n2c(i+1, state->order));
+                else
+                    printf(".");
+            }
+            printf(" ");
+        }
+        printf("\n");
+    }
+    printf("\n");
+}
+
+#endif
+
+static void pdiff(int diff)
+{
+    if (diff == DIFF_IMPOSSIBLE)
+        printf("Game is impossible.\n");
+    else if (diff == DIFF_UNFINISHED)
+        printf("Game has incomplete.\n");
+    else if (diff == DIFF_AMBIGUOUS)
+        printf("Game has multiple solutions.\n");
+    else
+        printf("Game has difficulty %s.\n", unequal_diffnames[diff]);
+}
+
+static int solve(game_params *p, char *desc, int debug)
+{
+    game_state *state = new_game(NULL, p, desc);
+    struct solver_ctx *ctx = new_ctx(state);
+    struct latin_solver solver;
+    int diff;
+
+    solver_show_working = debug;
+    game_debug(state);
+
+    latin_solver_alloc(&solver, state->nums, state->order);
+
+    diff = latin_solver_main(&solver, DIFF_RECURSIVE,
+                             DIFF_LATIN, DIFF_SET, DIFF_EXTREME,
+                             DIFF_EXTREME, DIFF_RECURSIVE,
+                             unequal_solvers, ctx, clone_ctx, free_ctx);
+
+    free_ctx(ctx);
+
+    latin_solver_free(&solver);
+
+    if (debug) pdiff(diff);
+
+    game_debug(state);
+    free_game(state);
+    return diff;
+}
+
+static void check(game_params *p)
+{
+    char *msg = validate_params(p, 1);
+    if (msg) {
+        fprintf(stderr, "%s: %s", quis, msg);
+        exit(1);
+    }
+}
+
+static int gen(game_params *p, random_state *rs, int debug)
+{
+    char *desc, *aux;
+    int diff;
+
+    check(p);
+
+    solver_show_working = debug;
+    desc = new_game_desc(p, rs, &aux, 0);
+    diff = solve(p, desc, debug);
+    sfree(aux);
+    sfree(desc);
+
+    return diff;
+}
+
+static void soak(game_params *p, random_state *rs)
+{
+    time_t tt_start, tt_now, tt_last;
+    char *aux, *desc;
+    game_state *st;
+    int n = 0, neasy = 0, realdiff = p->diff;
+
+    check(p);
+
+    solver_show_working = 0;
+    maxtries = 1;
+
+    tt_start = tt_now = time(NULL);
+
+    printf("Soak-generating an %s %dx%d grid, difficulty %s.\n",
+           p->adjacent ? "adjacent" : "unequal",
+           p->order, p->order, unequal_diffnames[p->diff]);
+
+    while (1) {
+        p->diff = realdiff;
+        desc = new_game_desc(p, rs, &aux, 0);
+        st = new_game(NULL, p, desc);
+        solver_state(st, DIFF_RECURSIVE);
+        free_game(st);
+        sfree(aux);
+        sfree(desc);
+
+        n++;
+        if (realdiff != p->diff) neasy++;
+
+        tt_last = time(NULL);
+        if (tt_last > tt_now) {
+            tt_now = tt_last;
+            printf("%d total, %3.1f/s; %d/%2.1f%% easy, %3.1f/s good.\n",
+                   n, (double)n / ((double)tt_now - tt_start),
+                   neasy, (double)neasy*100.0/(double)n,
+                   (double)(n - neasy) / ((double)tt_now - tt_start));
+        }
+    }
+}
+
+static void usage_exit(const char *msg)
+{
+    if (msg)
+        fprintf(stderr, "%s: %s\n", quis, msg);
+    fprintf(stderr, "Usage: %s [--seed SEED] --soak <params> | [game_id [game_id ...]]\n", quis);
+    exit(1);
+}
+
+int main(int argc, const char *argv[])
+{
+    random_state *rs;
+    time_t seed = time(NULL);
+    int do_soak = 0, diff;
+
+    game_params *p;
+
+    maxtries = 50;
+
+    quis = argv[0];
+    while (--argc > 0) {
+        const char *p = *++argv;
+        if (!strcmp(p, "--soak"))
+            do_soak = 1;
+        else if (!strcmp(p, "--seed")) {
+            if (argc == 0)
+                usage_exit("--seed needs an argument");
+            seed = (time_t)atoi(*++argv);
+            argc--;
+        } else if (*p == '-')
+            usage_exit("unrecognised option");
+        else
+            break;
+    }
+    rs = random_new((void*)&seed, sizeof(time_t));
+
+    if (do_soak == 1) {
+        if (argc != 1) usage_exit("only one argument for --soak");
+        p = default_params();
+        decode_params(p, *argv);
+        soak(p, rs);
+    } else if (argc > 0) {
+        int i;
+        for (i = 0; i < argc; i++) {
+            const char *id = *argv++;
+            char *desc = strchr(id, ':'), *err;
+            p = default_params();
+            if (desc) {
+                *desc++ = '\0';
+                decode_params(p, id);
+                err = validate_desc(p, desc);
+                if (err) {
+                    fprintf(stderr, "%s: %s\n", quis, err);
+                    exit(1);
+                }
+                solve(p, desc, 1);
+            } else {
+                decode_params(p, id);
+                diff = gen(p, rs, 1);
+            }
+        }
+    } else {
+        while(1) {
+            p = default_params();
+            p->order = random_upto(rs, 7) + 3;
+            p->diff = random_upto(rs, 4);
+            diff = gen(p, rs, 0);
+            pdiff(diff);
+        }
+    }
+
+    return 0;
+}
+
+#endif
+
+/* vim: set shiftwidth=4 tabstop=8: */