Warmonger

[Xog]

By the same team bringing you Jumpgate: Evolution, NetDevil has the free to download, and free to play, Warmonger.

http://www.warmongergame.com/

I haven't tried it yet, but I will tonight. It's a shoot'em up, originally designed for Nvidia card testing. Looks fun to goof around with - it has destructable environments :P