Half-Life is a science fiction first-person shooter video game developed by Valve Software and the company's debut product. First released by Sierra Studios on November 19, 1998, the game was also released for the PlayStation 2 on November 14, 2001. Valve, set up by former Microsoft employees, had difficulty finding a publisher, with many believing that the game was "too ambitious". Sierra On-Line eventually signed the game after expressing interest in making a 3D action game. The game had its first major public appearance at the 1997 Electronic Entertainment Expo. Designed for Microsoft Windows, the game uses a heavily modified version of the Quake engine, called GoldSrc.