At the start of a new game, a random game map is generated on a square grid basis. The map normally consists of numerous islands, although a variety of algorithms were used in different versions of the game, producing different styles of maps. Randomly distributed on the land are a number of cities. The players start the game controlling one of these cities each. The area immediately around the city is visible, but the rest of the world map is blacked out.
The city can be set to build armies, aircraft, and various types of ships. Cities take a particular number of turns to produce the various units, with the armies typically being the most rapid. Players move these units on the map to explore the world, typically seeing the land within a one square radius around the unit. As they explore they will find other cities, initially independent, and can capture them with their armies. The captured cites are then set to produce new units as well.
As the player's collection of cities expands, they are able to set aside some to produce more time-consuming types, like battleships. Ultimately they have to use these forces to take all the cities on the map, including those of the other players, who are often run by the computer's game engine.
Bright's first version was written around 1977 in the FORTRAN programming language for the PDP-10 computer at Caltech. This version was spread virally to other PDP-10s, which were common timesharing systems at the time. Later, Bright recoded this in assembly language on a Heathkit H11 and made it available commercially. He sold two copies.
At some point, someone broke through the security systems at Caltech, and took a copy of the source code for the FORTRAN/PDP-10 version of the game. This code was continually modified, being passed around from person to person. Eventually, it was found on a computer in Massachusetts by Herb Jacobs and Dave Mitton. They ported the code to the VAX/VMS operating system and, under the alias of "Mario DeNobili and Paulson" submitted the program to DECUS, a large user's group. DECUS programs were often installed on new DEC computers at the time of delivery, and so Empire propagated further. Eventually, Bright heard of this, and in 1983 contacted DECUS, who subsequently credited Bright in the catalog description of the program and re-added his name to the source code.
In 1984, Bob Norby from Fort Lauderdale, Florida, ported the DECUS version from the VAX to the PC as shareware. In 1987, Chuck Simmons re-implemented the game in C using the UNIX curses library for its supports of many character-cell terminals. Eric S. Raymond maintains a copy of this version and shared some version with open-source projects.
After this, Bright recoded the game in C on an IBM PC. With low commercial expectations, he submitted an announcement to January 1984 BYTE Magazine's "Software Received" section, and received a flood of orders. After writing to many software companies (including Brøderbund, Sirius Software, Simon & Schuster, subLOGIC, Epyx and MicroProse), he licensed the game to a small software company named Interstel, who hired Mark Baldwin to add a graphic user interface. Starting around 1987, Empire: Wargame of the Century on the Atari ST, Amiga, Commodore 64, Apple II, Macintosh and DOS was produced.
In its review of the game, Computer Gaming World noted the improved UI, saying "the playability of an already successful system has been significantly enhanced". The game would later receive the magazine's "Game of the Year" award for 1988; in 1989 the magazine named Empire to its Hall of Fame for games readers rated highly over time, with a final score of 9.71 out of 12, in 1990 readers voted for the game as their "All-Time Favorite", a 1991 magazine survey of strategy and war games gave it four and a half stars out of five, and a 1993 survey in the magazine gave the game three stars out of five. Compute! agreed with the warning on the game box of the its addictiveness, stating that the game combined aspects of exploration and strategy. The magazine also praised the UI, and concluded "this is a superb, addictive game". Jerry Pournelle of BYTE also agreed about the addictiveness. While stating that the UI was "not as good as I'd like", he concluded that Empire "tempts you to play a little longer and find out what's going to happen next". The Atari ST version of the game was reviewed in 1988 in Dragon #131 by Hartley, Patricia, and Kirk Lesser in "The Role of Computers" column. The reviewers gave the game 4 out of 5 stars. The Lessers reviewed the MS-DOS version of the game in 1989 in Dragon #142, and gave the game 4 out of 5 stars.
In the early 1990s, Mark Baldwin and Bob Rakowsky rewrote the game, calling it Empire Deluxe for DOS, Mac OS, and Windows, released in 1993 with New World Computing as the publisher. Empire Deluxe sustained the old game play of Interstel's version in a standard game, while adding a basic version for beginners, and advanced game with new units such as the Bomber and Armor and maps sizes up to 200x200.
An expansion pack, Empire Deluxe Scenarios, was produced later in 1993, including a map and scenario statistics tool, a map randomiser tool (as random maps were present in the Interstel version, but lacking from Empire Deluxe), upgrade patches for both DOS and Windows versions and a collection of 37 scenarios (with accompanying maps) from "celebrity" designers, many of them famous in the games industry including Will Wright, Jerry Pournelle, Jim Dunnigan, Johnny Wilson (Computer Gaming World editor), Gordon Walton, Don Gilman (Harpoon series architect), Trevor Sorensen (Star Fleet series designer), and the game's authors Mark Baldwin and Bob Rakosky.
Computer Gaming World in 1993 called Empire Deluxe "a welcome addiction (sic) to the library of every serious strategy gamer". A 1993 survey in the magazine of wargames gave the game four stars out of five, noting flaws but stating that "Yet, I keep on playing". It enjoyed great success, and was noted as one of Gamespy's Greatest Games of All Time. Empire Deluxe was reviewed in 1993 in Dragon #195 by Hartley, Patricia, and Kirk Lesser in "The Role of Computers" column. The reviewers gave the game 4 out of 5 stars.
Computer Gaming World in 1993 stated that Empire Deluxe Scenarios offered "a lot of value" to the game's fans.
Dan Bunten, best known for the famed M.U.L.E., released a PC version of Empire in 1992 under the name Global Conquest. Similar to other versions like Empire Deluxe, Global Conquest added a number of new unit types, an upgraded graphical display, and a terrain system that affected movement and combat. In addition to the time needed to build units, there was also a basic economic model where cities generated money to sustain the units in the field. This placed limits on the number of units in the game. In order to shake up the gameplay, the game also included random events that affected one or more of the players, and had a system to carefully balance these events so one player was not impacted by them more or less than the others. Most notable, however, was the addition of a multiplayer mode supported over modems.
In the Winter of 2002, Mark Kinkead of Killer Bee Software purchased the rights for Empire Deluxe from Mark Baldwin and Bob Rakowsky, and in 2003 produced a new version called Empire Deluxe Internet Edition a.k.a. EDIE for Windows. This was essentially a port of the code Baldwin and Rakowsky produced in 1993, with few changes, such as slightly increased the map size (255x255), but did not add any new rules. The company produced several other editions for Windows, Android, and iOS.
In 1995, New World Computing published a sequel named Empire II: The Art of War. While the original had been a turn-based strategy, Empire II was shifted towards turn-based tactics: there was no more empire-building and production of units, but the complexity and realism of battles were enhanced with features such as morale rules and various degrees of damage. The playable campaigns consisted of a collection of diverse historical or fictional battles. The game editor feature was enhanced by allowing the user to design not only new maps and campaigns, but also new units with new graphics and sounds.
There are ports for modern PC operating systems available for free download at Walter Bright's Classic Empire webpage.