Cube Colossus presents a fairly standard arena shooter but switches things up with a novel control scheme. The mouse moves your ship. See the blue arrow in the screenshot? That's your mouse pointer. Move it around and your ship follows it, so there's a little bit of lag as it trails along behind.
You use WASD to target the enemies, initialising a lock-on and allowing you to mash the left mouse button to fire.
There's also a whole anime-influenced story, told through conversational cut-scenes... but yeah, don't worry about that, there's more than enough pew-pew-pewing to keep you going.
Cube Colossus [Newgrounds]