Developers: Joar Jakobsson, James Primate
Platforms: PC, Mac
I've shared screenshots of Rain World before and discussed the game back in October. It's a game I've been followed for a while and since that preview last year, it has made great progress.
Kickstarter, with potential additions including new and more intelligent enemies, a fleshed out single player campaign, and greater overall polish. You can follow Rain World's development on TIGForums and vote for the game on Steam Greenlight.