The Higher I get up on this list, the more excited I get to write about it. Left 4 Dead is special in that it does one thing and one thing only; put you in the zombie apocalypse that we all dread (and secretly hope for), and it does it well. This is also a good example of a game whose assets all come from a tight multiplayer experience; simply playing this game by yourself and beating all four of the games will not do. You need to play this with friends. It is an absolute must.
Whether or not you consider that the game’s greatest strength or weakness is up to you, really, but in my case I find it to be a strength. Playing the game, working together to both survive and to get achievements, yelling at each other, trying to get to safety as soon as possible, and actually making you care when one of your teammates falls is something that few games have done well. When I play the game, I want everyone to make it out alive. I just happen to be that guy that will just run to the helicopter and abandon you, though.
Although there are only four campaigns to go through, those campaigns have and immense amount of replay value. The fact they are as short as they are means if you and some friends have nothing better to do before, say, going to see a movie, you can just play a game for an hour (or even shorter, if you want), and that in of itself gives it a great sort of ability to be satisfying and brief at the same. I wouldn’t recommend it if you don’t have any friends to play with, but if you do, this game is one that you can just pop in whenever you have people over and not trade in any sort of gameplay (like in say, Wii Sports), and there’s just something to be said about that.