OpenDungeons is described as 'Open source, real time strategy game sharing game elements with the Dungeon Keeper series and Evil Genius. Players build an underground dungeon which is inhabited by creatures. Players fight each other for control of the underground by indirectly commanding' and is a RTS game in the games category. There are more than 10 games similar to OpenDungeons for a variety of platforms, including Windows, Linux, Steam, Mac and Flatpak apps. The best OpenDungeons alternative is Evil Genius. It's not free, so if you're looking for a free alternative, you could try OpenDungeonsPlus or UnderMaster. Other OpenDungeons like games are Dungeon Keeper 2, Black and White, The Castle Doctrine and War for the Overworld.