The action-role playing game Deus Ex (2000) was developed over 34 months by a team of approximately 20 people at the American company Ion Storm. Team director and producer Warren Spector began to plan the game in 1993 after releasing Ultima Underworld II with Origin Systems and attempted the game both there and at Looking Glass Technologies before going into production with Ion Storm. Official preproduction began around August 1997, lasted for six months, and was followed by 28 months of production. Spector saw their work as expanding on the precedent set by Origin, Looking Glass, and Valve.
In preproduction, six people from Looking Glass's Austin studios focused on the setting ahead of the game mechanics, and chose a story centered around prominent conspiracy theories as an expression of the "millennial madness" in The X-Files and Men in Black. Spector felt that the development process's highlights were the "high-level vision" and length of preproduction, flexibility within the project, testable "proto-missions", and Unreal Engine license. Their pitfalls included the team structure, unrealistic goals, underestimating risks with artificial intelligence, their handling of proto-missions, and weakened morale from Daikatana's bad press. The game was published by Eidos Interactive and released on June 23, 2000 for Windows 95 and later versions, whereupon it earned over 30 "best of" awards in 2001.