Recently, I've become interested in Left 4 Dead 2. Known as the sequel to the original Left 4 Dead, pitched as "the zombie apocalypse you can play with your friends", the game takes four players (or at least one player followed by bot players) through the Southeastern United States in a bid to find evacuation during a zombie apocalypse.
(Since there's plenty of graphic imagery in even just the opening cinematic, I'll leave it to y'all to find images and videos of the game. Obviously, it's not for the weak-hearted)
Almost everything about this game is awesome. The characters, for example, each have backstories and personalities that are revealed throughout the game. In fact, even the undead and the game environment seem to be well fleshed out; each map has its distinct atmosphere - thanks to area-specific music and exquisite lighting - and there are uncommon infected (e.g. riot police, hazmat suits) for each of them.
Another thing worth mentioning is the event director for the game. It's an embedded program that helps make each run through the game a different one through manipulating the map (i.e. changing the positions of the props and spawning hordes of infected). It really helps keep the game fresh, even in stagnant areas.
If anyone has the guts to try it out, the game's available on Amazon and Steam. We can play together sometime.