My god, best $15 I've ever spent. It's cross platform via gamespy (PC, xbox, and PS3) and just freaking fun to play. It's tower defense with a lot of options. I played with two other guys last night for almost 7 hours straight. Just too much fun. Highly recommended if anyone is on the fence. Currently playing the wizard, level 12 or so. I am maxing all my towers first (health, attack speed, base damage, AoE, range). I get MVP quite a bit.
Corsair 600T | ASUS P8P67 PRO | Intel 2500k @ 4.4Ghz | EVGA 560 TI | G.SKILL Ripjaws Series 8GB | Corsair HX650 650W