Nation Red

[deluxulous]

"Nation Red is an ultra fast infinite play arena-based shooter providing an exceptional close-quarter battlefield experience. Fight thousands of zombie mutants and their bosses in frantic bloody gameplay." - Steam

Perks if you get it on steam:
Steam Hammer - Weapon that rips the skin off of enemies (HURR HURR PUN)
New Levels/Enemies
Pneumatic Destroyer - Detonates the Thumper once they are surrounded by zombies

Played the demo, I loved it.