Somehow I had never heard of this game until today. Revolver 360 RE:ACTOR is your standard 2.5D bullet hell shooter, but with a twist: you can literally revolve the world around you. Pressing the left or right trigger will rotate the world up or down around the player's ship. Your ship continues to be controlled on 2D plane, with the rotation technique being used to avoid enemy fire and obstacles. It adds a whole new dimension to the gameplay, while still retaining the precise 2D movement which makes the genre work so well.
It's both innovate and a fun game; I just played for couple of hours straight. Maybe I have even found a new Ikaruga. The game is on sale on GOG at the moment if anyone else is interested in giving it a try.