Most zombie shooters fire waves of enemies at you until you’re finally overwhelmed, but you stay stuck in one area the whole time. “Mutant Zombie Onslaught” moves away from that idea, instead having you clear out room after room, corridor after corridor, making it feel a bit more like a Diablo, or a Gauntlet. It gives you that sense of exploration that’s missing from arena wave-shooters, and I liked that about it. Power-ups don’t last forever in this game either, when you run out of ammo for the good stuff you have to downgrade back to your basic weapons, which gives you an incentive to use those special weapons more effectively.
The room by room exploration makes it feel a whole lot more like a zombie movie than the wave shooters that typify the zombie game genre, and I appreciated the randomly generated levels and the availability of local co-op (for 2-4 players. Add it all up, and it earns this 80 Microsoft Point effort a recommendation.
Here’s what the developer (Photonic Games) has to say about the game:
“The year is 2012 and the world as we know it has ended. A virus sent from the depths of Hell has decimated humanity. Genetic mutations caused by the virus have turned many of those remaining into mindless zombies with dangerous mutant powers. Can you survive the zombie onslaught and save humanity from Armageddon ?”
Writings of Mass Deduction 
Fun game great find.
Glad you enjoyed it, David. You’re my longest-running regular commenter, so I’m always especially happy when you discover something here you weren’t previously familiar with (if indeed, this is one such game, since you didn’t expressly say you weren’t already familiar with it). :)
This game is crazily addictive. It seems just difficult enough that you are in danger some of the time, but easy enough that it doesn’t just chew you up repeatedly. It is a very fun game, and much better than most of the wave shooters on XBLIG. My ever-decreasing wallet thanks you! : 0 Well, decreasing at about a dollar at a time …