Left 4 Dead

(Image Courtesy of SlashGamer)

Left 4 Dead is a first-person-shooter developed by Turtle Rock Studios, and published by Valve for the PC and XBox 360. Players experience a zombie outbreak, fighting their way through a variety of levels in order to survive.

While Left 4 Dead does have a single-player mode, where the player is helped out by AI-controlled teammates, it is usually played with others. In the game's Campaign mode, up to 4 people can play together as members of a group of survivors, who are struggling to survive due to the recent outbreak of the "Green Flu". The victims of the Flu, called the Infected, are essentially zombies, and even the characters within the game note this. The survivors fight their way from safe room to safe room, while picking up a variety of weapons and helpful items (such as med packs, pain pills, and explosives). A great emphasis is placed on teamwork, with the AI in charge of spawning enemies and items rewarding the players if they act well together, and punishing them if they don't. Besides fighting off the regular Infected, the players must also face "special Infected", who have been so mutated by the Flu that they have developed special abilities, such as the ability to shoot Infected-attracting bile, to pounce from great heights onto the players, to grab and pull players away from a distance using their whip-like tongues, and more. These Special Infected can also be played as by the players: in Versus mode, 4 players play as survivors while the other 4 play as Special Infected, switching off after each portion of the level to see who can do the best and acquire the most points.

There are many ways Left 4 Dead could have been digitally prototyped. What is most likely is that the gameplay, the individual Special Infected, and the AI Director that manages enemy/item spawning were prototyped separately, before being combined later on. The gameplay prototype would not require the AI Director's features, for they'd make the game too unpredictable to test at first, and the Special Infected were probably added as they were tested and their concepts finalized. With the gameplay prototype including just enough features to represent gameplay, those coding the AI director would have more time to get a rough version of it working in order for it to be tweaked before the final version was made. Having separate, but connected, groups working on the different prototypes would have allowed the most work to be done, and it is for that reason that I believe that Turtle Rock Studios did something similar to what I have proposed.