+static game_params *decode_params(char const *string)
+{
+ game_params *ret = default_params();
+
+ ret->w = ret->h = atoi(string);
+ while (*string && isdigit(*string)) string++;
+ if (*string == 'x') {
+ string++;
+ ret->h = atoi(string);
+ }
+
+ return ret;
+}
+
+static char *encode_params(game_params *params)
+{
+ char data[256];
+
+ sprintf(data, "%dx%d", params->w, params->h);
+
+ return dupstr(data);
+}
+
+static config_item *game_configure(game_params *params)
+{
+ config_item *ret;
+ char buf[80];
+
+ ret = snewn(3, config_item);
+
+ ret[0].name = "Width";
+ ret[0].type = C_STRING;
+ sprintf(buf, "%d", params->w);
+ ret[0].sval = dupstr(buf);
+ ret[0].ival = 0;
+
+ ret[1].name = "Height";
+ ret[1].type = C_STRING;
+ sprintf(buf, "%d", params->h);
+ ret[1].sval = dupstr(buf);
+ ret[1].ival = 0;
+
+ ret[2].name = NULL;
+ ret[2].type = C_END;
+ ret[2].sval = NULL;
+ ret[2].ival = 0;
+
+ return ret;
+}
+
+static game_params *custom_params(config_item *cfg)
+{
+ game_params *ret = snew(game_params);
+
+ ret->w = atoi(cfg[0].sval);
+ ret->h = atoi(cfg[1].sval);
+
+ return ret;
+}
+
+static char *validate_params(game_params *params)
+{
+ if (params->w < 2 && params->h < 2)
+ return "Width and height must both be at least two";
+
+ return NULL;
+}
+
+static int perm_parity(int *perm, int n)