Freeciv

It maybe a small? problem when do make_island and map generator is island or fair.
e.g. In classic ruleset with default server settings except minplayer = 0 and generator = island (54x72 map, steepness stays 30), mountain_pct is 19% (desert, forest, jungle, swamp_pct is 7, 17, 2, 6).
When steepness = 61, mountain_pct is 26% (desert, forest, jungle, swamp_pct is lowered to 4, 12, 1, 4, because value factor is lowered).
When steepness = 100, mountain_pct is 15% (desert, forest, jungle, swamp_pct is 1, 4, 0, 1, so grassland / plains / tundra is placed instead).

(server/generator/mapgen.c adjust_terrain_param)

  int polar = 2 * ICE_BASE_LEVEL * game.map.server.landpercent / MAX_COLATITUDE;
  float factor = (100.0 - polar - game.map.server.steepness * 0.8 ) / 10000;

  mountain_pct = factor * game.map.server.steepness * 90;