The indie rhythm-schmup with a twist Retro/Grade has set a release date for August 21 on the PlayStation Network. The game plays in reverse, so you'll actually be seeing your battle against a massive alien invasion backwards. Yes, it sounds confusing.
Instead of firing your shots, you'll un-fire them to the beat of the music, and dodge enemy shots as they head back to the ships that fired them. If you'd like, you can play the game with a guitar controller instead of the standard DualShock controls, but developer 24 Caret hasn't detailed which controllers will be supported. The announcement on the PlayStation.Blog also mentions that the soundtrack will be available on PSN.
If you're still having trouble grasping the concept, check out a new trailer for the game.