One of the most heartfelt talks I saw at GDC this year was the Fract session, which basically underlined how much time, effort, and ARGH OH GOD can go into making a commercial version of a game that had already won an award at the IGF. The prototype might have captured the imagination of judges, but the concept for the full game was still very much up for grabs, and the Fract team ending up causing themselves all kinds of heartache by building, scrapping, and rebuilding the game they wanted it to be. Now though the synthesizing world of light and music is on the final straight, and they're expecting to release in 2013. The music the following trailer was composed in-game, by playing with the game's tools. Marvelous stuff.
The game is up on Greenlight, and there are surely few other candidates as clearly deserving of a thumbs up.