OpenDungeons is an 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 their creatures, directly casting spells in combat, and luring enemies into sinister traps.
The game is developed by a friendly community of developers and artists, and has now reached a quite playable and enjoyable status after more than 6 years of development.
Licensing: The code in under the GPLv3 license (except for one bundled dependency, angelscript, which is under the zlib license) [1]. The art assets and non-code text files are under various DFSG-free licenses: CC-BY-SA 3.0, CC-BY 3.0, CC0, OFL, GPLv2+, GPLv3+, MIT [2].
[1] https://github.com/OpenDungeons/OpenDungeons/blob/development/LICENSE.md [2] https://github.com/OpenDungeons/OpenDungeons/blob/development/CREDITS