Empire is a 4X wargame created in 1972 by Peter Langston, taking its name from a Reed College board game of the same name. It was initially created by Langston in BASIC on an HP2000 minicomputer at Evergreen State College. When the host computer was retired, the source code to the game was lost. Subsequently, two other authors each independently wrote a new version of the game, both named Empire. In the decades since, numerous other versions of Empire have been developed for a wide variety of platforms. The game is turn-based, with players giving orders at their convenience, and in some versions then executed simultaneously by the game server at set intervals ranging from a few hours to once per day. The game world consists of "sectors", which may be designated as agricultural, industrial, etc. There are dozens of unit types requiring a variety of raw and manufactured materials for their creation. "Blitz" games may last a few hours, typical games a few months, and some larger games up to a year. Less