The shoot 'em up wizards at Treasure are hoping to bring the classic Ikaruga to PC, but first must survive the Thunderdome of Steam Greenlight. The colour-swapping bullet hell shmup first hit arcades in 2001 but has proved enduringly popular for what's really a niche genre, later coming to Dreamcast, GameCube, Xbox 360, and Android.
The trick to Ikaruga is that all enemy ships and bullets are either black or white, and your ships can switch from one to the other. You absorb all shots the same colour as you and deal extra damage to others, so you flit between the two, dodging, shooting, and 'sploding.
This PC port is based upon the 2008 Xbox Live Arcade release, which ruffled a few feathers amongst the shmup hardcore for making a few minor changes but should be just dandy for most. It will support controllers as well as keyboard and mouse.
Go vote for it if you're interested.