Left 4 Dead is mostly fun when played cooperatively and the game will fulfill your wish of being caught in a Zombie Apocalypse from both perspectives with tons of guns and hordes of Zombies at your disposal. Unpredictable & relentless enemies make it imperative to have human teammates in harder difficulty modes, but you can't complain about killing zombies alone either. The game also offers a variety of gameplay modes which will keep you interested for a while.
#6. Plants vs Zombies
Developed by Popcap, Plants vs Zombies is definitely up there amongst the best of the best tower defense games. The basic objective in the game is that players have to defend their house from brain hungry Zombies, by strategically using combat-ready plants to your advantage. The game has an incredible variety of both Plants and Zombies, in different shapes and sizes. Plants vs Zombies on the 360 is the most feature packed versions of the game i.e available on many other platforms. The ingenious reward system, game design, and audio are simply top notch in Plants vs Zombies. If you like Zombies and enjoy Tower defense games, we simply can't recommend this game enough.
#5. COD: World at War
The addition of the Nazi Zombie game mode sure was a welcome one to the otherwise been there done that WW game. Unlocked after completing the game, it puts up to 4 players in an abandoned house with some barricades between you and the Nazi Zombies. As you progress further in this mode it gets more intense and satisfying as waves of undead keep piling on, while unlocking new weapons and locations in the house.