The watershed came in the form of a military training game, called Marine Doom (1998), created for the purpose of training soldiers in teamwork and decision making skills when live training time and opportunities were limited during peaceful times. Instead of creating the video game from scratch, the U.S. Marine (in-house) development team decided to modify (or, mod) a COTS game, Doom (1992), to take advantage of the game mechanics and resources already present in the game engine, as well as to reduce production cost and time. This game modification process—whereby a COTS game’s own engine is re-used to create a “home-brew” (and very much playable) game—has come to be known as modding among the gamers. Since then, the U.S. Marine Corps have gone on to create other military game modules (or mods), including the highly successful America’s Army, with over 26 versions released since its debut in 2002. Gamers have easy access to thousands of game mods (made from a plethora of COTS games) that were distributed through repositories and websites created just for mod enthusiasts—for example, the Vault Network (http://www.moddb.com).