Sequel to the Dreamcast game - looks to be an MMO in the works. It's essentially DoTA in space. The game is in VERY early Alpha, very little content is implemented at all, but it seems fairly cool so far. It looks like they're auto-accepting into Alpha(at least as of yesterday when I signed up).

Site: http://www.armadaonline.com/index.html

It's a top-down 2d game using sprites, though the graphics are fairly decent using bloom and such. Looks like a fun game to pass some time.