Sniper Elite: Nazi Zombie Army
In this game you play one to four players and shoot Nazi zombies while moving to the next safe house. Yes it's Left 4 Dead with Nazi Zombies.
Sniper Elite: Nazi Zombie Army 2
One would think this would be an improvement like Left 4 Dead 2 was compared to L4D but this it's really only more levels and more zombies.
Sniper Elite III
Feels like a good step forward for this series. Less linear levels makes it more fun to explore and the stealth system is much better.