- Original Keen Dreams source-code liberated
 - Also check out: CloneKeen, Omnispeak & Commander Genius
 - CaveExpress liberated (2d physics game)
 - Pixel Dungeon RogueLike open-sourced (Android only)
 - X-Com: Apocalypse engine reimplementation
 - Libre content replacement project for Gish
 - Stein's Gate Visual Novel Engine reimplementation
 
Big tease: Icculus works on open-sourcing a game and it seems to be a relatively new title as it includes steamworks support.
Please comment below if you know of other recent open-sourceing efforts ;)