Kinda disappointed in myself for taking this long to discover this game. I must say it's well worth the 10 dollars over steam/400 points on XBL.
Primer: Don't rely solely on the demo music, it doesn't do the game nearly enough glory. Also, as a major warning, DO NOT play this game while fatigued/in the dark/ or if you're prone to seizures, this game is a lightshow on steroids. Trust me on this one, I had a bad headache today from playing while tired last night. It's like a watered down hangover. (Not that I'd know what one feels like since I don't drink. >_>)
It's really hard to describe, but it's like taking Asteroids gameplay and mixing it with the properties of Guitar Hero and Touhou, but much more customizable. Yeah, weird combo; by that, I mean the levels are your music. Literally EVERY SONG in your digital music collection is a different level and a different experience, as the level is crafted by the music itself. The magnitude of your lasers is determined by how intense the music is at the time of firing. The music also determines how many enemies appear on screen and in what pattern they move. It also determines your boss fights during the track, so usually, you fight the bosses at the good parts of the song, which is really cool. (Perfect Situation by Weezer is just full on SENSATION!) C'mon, you know the good parts of your favorite songs.
And what's better is that this is only the first installation. The creator says he's got big plans for the next.... volume? version?....chapter? Eh, I dunno, but there's gonna be more - hopefully even a multiplayer mode - soon.
But yeah, I love it, and recommend it to anyone who likes gaming to music they like.