Sure, it's a shmup and it's a sequel to the famous Sin and Punishment that was released in Japan a while ago. The original only recently came stateside via the Nintendo download service on the Wii, previously it was Japan exclusive.
Anyways, in the game you play as either a guy or a girl and you are sort of on rails but you can move around. So it's more of a fixed camera that only allows you to float around the screen. You are constantly bombarded with bullets, monsters, lasers, flying heads, etc. and you need to kill everything. You get timed bombs and an unlimited supply of bullets. It is crazy fun that requires a lot of precise movements. Here is the cover:
