Quake3World

I usually don't post topics like this, but this game I ran across is just killer. Jets and Guns is a side-scrolling, high-octane, independantly developed space shooter that is super heavy on the fun factor and is ultra-extreme-like-blowing-stuff-up-and-shit. Trust me, just download the demo and try it yourself. Its fun as hell.

that looks fuckin fun

Heh, I bought that a while ago. It's got a lot of longevity.
Think I posted about it here too, or it may have been over at raw's place.
Also, check out Machinae Supremacy's website.
They did the rather fantastic music for the game, and it can all be downloaded for free from their site, as well as other stuff.

Edit: Oh, and to clarify, DOWNLOAD THE DEMO NOW.
The reason it's got a lot of longevity is because it's a damn good challenge, great fun, and looks absolutely spectacular.
You'll want to play over and over again trying to beat your high score, or in an effort to discover the perfect weapon combo.

this is ownage, but how do i upgrade my weapon cooling system?

I'm not sure if you can in the demo; I think it's one of the limitations.