this game is brilliant. it blends multiple ideas to create a system that has all the best bits of tower defense (unit placement and waves of enemies), shmup (LAZORS EVERYWHERE, manual aim control), and rts (resource management) to make something that isn't quite any of them. the cartoon-y art style, unique soundtrack, and jokes throughout don't hurt things, either. oh, and the latest build supports online multiplayer =D.
because it's still in beta, it's on sale (75% off, as of this writing) right now over on
desura, so, if this at all piqued your interests, you should definitely go snag a copy!
(oh, and, if any of you happen to get it, feel free to poke me for some co-op)