Empire is a 4X wargame created in 1971 by Peter Langston, taking its name from the Reed College board game of the same name. In 1973, Empire resurfaced under the name Civilization on an HP2000 minicomputer at Evergreen State College. The game was written in interpreted BASIC and utilized extensions to the operating system. When the host computer was retired, the source code to Civilization was lost. Subsequently, two other authors each independently wrote a new version of the game, both named Empire.
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.