The Darius games are 2D side scroll spaceship fighter games. :) Twin has been the only one I've ever played so far, and it's a challenging one. I've seen the newest one, Darius Burst, is on PSP, but it may be another long while before I get that last generation handheld!

lol, Chemical Plant Zone is a tough one. Love, love, love the music from that level. I've heard some great remixes of that, including an Acapella version of it. I'm really, really going to have to think how I'll do differently with that one.