Hi there,
KeeperRL is an awesome GPL'ed game from miki151, that draws inspiration from both Dwarf Fortress und Dungeon Keeper.
Though the game is still in alpha according to its developer, it's already quite playable and fun! You can find binary downloads for the latest alpha on its website: http://keeperrl.com/
Here are a few screenshots:
Now, the developer has just started a crowdfunding campaign on Indiegogo for the final version of the game, KeeperRL 1.0.
The question arises of whether the end product will still be open-source or not. I asked the developer about it on his forum, and he's currently unsure about it: http://keeperrl.com/smf/index.php?topic=11.0
So please have a look at this game, and give your feedback on the forum page linked above. The ball is on our side to show that the FLOSS community would support such a project through crowdfunding if it stays free software (which doesn't necessarily imply free of charge, it's always good to remind it).