Zombies were (and still are) very popular in shooting and action games throughout the 2000s, but few games pulled off the undead better than Left 4 Dead. Developed by Valve, the company responsible for games like Half-Life, this cooperative FPS was as addictive as it was bloody. The idea was simple; four players shoot their way through levels packed with zombies, working together to take down the hardest of foes.
What made Left 4 Dead special was its random nature, spurred on by an artificial intelligence called “The Director”. The game would change the spawn-spots of certain high-danger zombies, alter objective locations, and more. This gave Left 4 Dead a big boost of replayability, making it a perfect co-op game that always felt exciting and unpredictable.