Microsoft Disk Operating System (or MS-DOS) is an Operating System for x86-based computers which was purchased by Microsoft. First released in 1981, the platform ended up running over 1,000 games, many of which were released on the Shareware model.
Some of the more well-known games for the system include Wolfenstein 3D, Prince of Persia, DOOM, Jazz Jackrabbit, Duke Nukem 3D, Warcraft: Ors & Humans, SimCity 2000, Command & Conquer, and Quake.