Space combat is the principal element of warfare in Master of Orion. Enemy ships face off in space and fight until one side either retreats or all of its ships are destroyed.
- Combat takes place on a 2D plane, with ships beginning at opposite sides of the arena, well outside each other's range.
- Ships fire upon each other automatically when in range, with special system being used by each player manually.
- The arena is usually populated with a number of asteroids and other obstacles, providing cover from enemy weapons. Their durability is not infinite and upon taking enough damage, the obstacles are destroyed.
- The biggest change occurs when space structures such as military outposts or battle stations are involved. These durable installations are completely immobile, but are heavily armored and armed. They virtually guarantee a planet's immunity to attack in early phases and even later on they can provide a significant obstacle.
- Ships that enter a Nebulae (clouds in space) in the arena will have their shields disabled but the nebulae also disorients incoming missiles. The nebulae are usually in the middle where the space structures are thus rendering their shields useless as they can't move out of it.