(XBL, PSN, PC)
I think this looks really awesome and well worth the $11 ($9.90 for pre-orders). Basically it is a co-op tower defense / action RPG hybrid but I refer you to the pages I linked above for a detailed description. I hope the developers keep it patched and provide new content regularly.
I can't seem to find a specific release date. Steam says November 2010, Impulse says 12/31/2010, GamersGate says 11/25/2010 and there doesn't seem to be an official date on their website. Delayed to January 2011. July? Maybe August?