Haunts: The Manse Macabre is a BSD-code/CC-BY-NC-SA-art Kickstarter-funded, turn-based RPG(?). There are still a few hours left to contribute to additional features.
Sintel: The Game, currently completely CCBY3-licensed, just had their first alpha release! They have original voice acting and all! (Although I did not manage to get it running on Linux yet).
Puzzle Moppet has been released under the WTFPL and I was able to replace all non-free textures and sounds. Now all we need is a repository coordinator.
Valyria Tear is a continuation of the jRPG Hero of Allacrost project with an active development blog.
Frogatto is a well-designed-code, beautiful-proprietary-pixel-art platformer. The developers started "making friends" on their blog by talking about projects they like.
reviewed in an extensive, illustrated article.