Screamer

The Screamer was a prototype Special Infected formulated early in Left 4 Dead ' s development. As such, he is the progenitor of Special Infected like the Witch and Boomer. Screamers were presented in-game as Infected humans bound in a restraining psychiatric-style straitjacket.

The idea for the Screamer was for him to lurk in different areas, much like the Witch, paying no attention to his surroundings until coming in contact with a Survivor whereupon, if sufficiently agitated, he would run away from Suvivors in an attempt to hide. If he succeeded in escaping, he emitted a loud scream that alerted a horde, causing an attack - thus, foreshadowing the later Boomer bile concept, and additionally helping to establish early on in production that the Common Infected are driven to extreme aggression as a response to loud noises. It was therefore important for the players to kill the Screamer before he could escape and call a horde. Since the Screamer was under physical restraint, he did not have the ability to mount any direct attack on Survivors.

As stated in the Developer Commentary, Screamers and Boomers co-existed for a time during development. At the time, the Boomer merely exploded when killed, causing damage to nearby Survivors, while the Screamer would attract hordes with his scream. Ultimately, the Screamer was cut from the game because he was deemed too difficult and confusing for the Survivors to spot and track down amongst a crowd of Common Infected. However, the idea of a Special Infected having an attack that attracts a horde was considered too good to go to waste, and the Boomer was then given its bile attack and its bile splash death effect.