Marine Doom

Marine Doom is a single-level PWAD for Doom II. It was designed for use by the US Marines, but in 1996 was made available for public download by Sergeant Daniel G. Snyder.

In the game, a fireteam, comprising four Marines, is supposed to accomplish a specific mission, the default being the destruction of an enemy bunker, although other scenarios such as a hostage rescue in a foreign embassy can be designed. In order to allow coordination of their movements, these soldiers play on separated computers in the same room. The fireteam consists of a Team Leader, two riflemen, and one machine-gunner.

Marine Doom was later superseded by the completely homebrew game America's Army.

History
In 1995, General Charles C. Krulak, Commandant of the USMC, issued a directive to use wargames for improving "Military Thinking and Decision Making Exercises". He charged the Marine Combat Development Command with the task of developing, exploiting and approving computer-based wargames to train U.S. Marines for "decision making skills, particularly when live training time and opportunities were limited."

A group of simulations experts in the Marine Corps Modeling and Simulation Management Office (based in Quantico, Virginia), including Lieutenant Scott Barnett as the project officer, obtained a commercial copy of Doom and started designing a fireteam simulation, which focused on mutual fire team support, protection of the automatic rifleman, proper sequencing of an attack, ammunition discipline, and succession of command.

Before its completion, their map was modified to work with Doom II v1.9.