A Hellish Development

Left 4 Dead was an improvement upon Valve's Source engine (a 3D game engine which they developed) and allowed them to work on many different things, such as the physics-based animation.  This allowed them to use a more realistic portrayal on characters' hair and clothing and let them improve upon the physics interaction with enemies.  This also allowed the characters to move more realistically.  Because of these improvements, the game was able to run smooth as all of the zombies continued to keep coming.  Valve also used some sort of advanced shadow rendering as well for the lighting aspects of the game.  Horror films were a big inspiration for Left 4 Dead too, and a lot of the time you can see how they affected how it added to the cinematic parts of the game.


During the testing and development of Left 4 Dead, there were lots of features that were removed from the game, like various types of zombies.  Because the game is meant for its replayability and fast action, Valve decided to take away the long introduction and many of the cut scenes and replaced them with some narratives so that the players would have more time to focus on the gameplay itself.