Master of Orion II: Battle at Antares (MOO2) is a 4X turn-based strategy game set in space, designed by Steve Barcia and Ken Burd, and developed by Simtex, who developed its predecessor Master of Orion. The PC version of the game was published by Microprose in 1996, while the Apple Macintosh version was published a year later by MacSoft in partnership with Microprose. The PC version was on sale as a download until late 2010 when Atari silently removed the game from their on-line store. While the game is no longer on sale directly from Atari copies can be found on Amazon and other stores. Despite its age the game still has a large fan-base and is still played online.
Master of Orion II won the Origins Award for Best Fantasy or Science Fiction Computer Game of 1996, and was well received, although reviewers differed about which aspects they liked and disliked. It is still used as a yardstick in reviews of more recent space-based 4X games.
Victory can be gained by military or diplomatic means. Major elements of the game's strategy include the design of custom races and the need to balance the requirements for food, production, cash and research. The user interface, which is mainly mouse-based but includes keyboard shortcuts, provides a central screen for most economic management and other screens that control research, diplomacy, ship movement, combat and warship design.
Long before the time in which the game starts, two extremely powerful races, known as the Orions and the Antarans, fought a war that devastated most of the galaxy. The Orions won and, rather than exterminate the Antarans, imprisoned them in a "pocket dimension". The Orions then departed from the galaxy, but left behind a very powerful robotic warship, the Guardian, to protect their homeworld. Whoever beats the Guardian gets military technologies which players cannot research for themselves and the opportunity to colonize the Orions' homeworld, which is usually the best planet in the galaxy in all respects.
Some time after the start of a game, the Antarans, breaking out of the prison dimension to which the Orions banished them, begin sending increasingly powerful fleets against players' colonies, simply to destroy rather than to invade. The only way to stop the Antarans' campaign of terror is to carry the battle to their home universe through a Dimensional Portal.