Wolfenstein
Silas Warner, an American programmer and an employee of software company Muse Software, was a pioneer of early video game development, especially the stealth genre. He had access to computers in college, and when he worked for the IBM Mainframe architectures before joining Muse Software. The computer he used for game-development, P.L.A.T.O., was one of the firsts with multiple functioning terminals and an example of early computer networks. Warner developed, with P.L.A.T.O., a series of classic video games like his flight simulator and arcade shooter. Inspired by the arcade shooter video game "Berzerk" and the 1961 war film "Guns of Navarone", he developed "Castle Wolfenstein", a stealth-adventure video game in which the player controls an unnamed American prisoner of war as he steals German files containing secret war plans, while avoiding, disarming or at times killing hostile guards and trying to escape the fortified Nazi stronghold 'Castle Wolfenstein', set in World War II. The game was published in 1981 by Warner's company M.U.S.E. Inc. (Muse Software).
Wolfenstein: Enemy Territory
Wolfenstein: Enemy Territory is a free and open-source multiplayer first-person shooter video game set during World War II. It was originally planned to be released as a commercial expansion pack to "Return to Castle Wolfenstein" and later as a standalone game. However, due to problems with the single-player aspect, the multiplayer portion was released on 29 May 2003 as a freeware standalone game. In January 2004, the source code for the game logic (not the game engine) was released to the benefit of its modding community.