Release should be this summer, during August, on PC and Xbox Live Indie Games.
I dont' know for now if the game will be free or not on PC, but I know it will cost ~80 points on XLID.
You can already try a little demo. Full game should contain more levels, more weapons, more enemies, and... less bugs I hope.
I've got lots of comments on this demo so I should be able to fix a lot of existing problems.
Stay tuned ;)