Master of Orion Wiki
Marines icon.png

Colony combat or ground combat is the brutal war for control of a planet between two warring empires - or the act of wiping out one using ship-based bombs.


  • Colony combat is simulated, using the relative strengths of both sides to achieve the result.
  • The attacker is limited to Marines brought in using troop transports (four units per). Dropping directly onto the surface of the planet, these troops fight to the bitter end. Their performance is determined by unlocked ground combat technologies (unlocked as tech achievements) and any innate racial traits. The defender has a more comfortable position, as on top of Marines stationed at marine barracks (if any), they can also employ armor units from armor barracks.
  • The alternative to conquering a planet is orbital bombardment. Firing indiscriminately, bombardment destroys population, colony structures, and any existing military units of the planet owner.
  • Any Marines left on the planet once it falls to the invader remain stationed as a permanent garrison, as transports cannot escape planetary gravity once deployed.


Marine Marine Unit.png
Powered Armor Marine Upgraded Marine Unit.png
Armored Tank Armor Unit.png
Battleoids Upgraded Armor Unit.png

Combat effectiveness[]

Name Image Effect Description
Laser rifle
Base combat rating: 0.05 The Laser Rifle is a hand-held weapon that increases the combat rating of ground troops by 5%. This bonus is replaced by, not cumulative with, those from more advanced rifles.
Neutron rifle
Base combat rating: 0.1 The Neutron Rifle is a hand-held weapon that increases the combat rating of ground Marines by 10. This bonus is replaced by, not cumulative with, those from more advanced rifles.
Phasor rifle
Base combat rating: 0.2 The Phasor Rifle is a powerful hand-held weapon that practically disintegrates opponents. This increases the combat rating of ground Marines.
Plasma rifle
Base combat rating: 0.3 The Plasma Rifle is the most powerful hand-held weapon known. It increases the combat rating of ground Marines. This bonus replaces those from less advanced rifles.
Powered armor
Infantry combat rating bonus: +0.1
Infantry hit point bonus: +1
Powered armor provides ground Marines with superior power and mobility by mechanically magnifying their natural strength. Marines equipped with powered armor have a bonus added to their combat rating.
Anti-gravity harness
Infantry combat rating bonus: +0.1 The Anti-Gravity Harness allows ground Marines to fly, substantially increasing their mobility and defense and improving ground combat.
Personal shield
Infantry combat rating bonus: +0.1 Personal Shields deflect both physical and energy attacks. They offer protection against most ground Marine attacks, increasing ground combat skills.
Armor hit point bonus: +1 Battleoids are giant robot fighting vehicles with power and mobility far beyond that of conventional tanks. This technology allows your Armor Barracks to build and support Battleoids. Battleoids have a ground combat rating higher than tanks.

Planetary defenses[]

Name Icon Cost Upkeep Requirement Effect
Marine barracks
Marine barracks.png
60 1 Generates 1 marine every 5 turns (used for planetary defense and troop transportation)
Armor barracks
Armor barracks.png
140 2 Generates armored units for defense (1 per 10 turns, 2 at start)
Space academy
Space academy.png
100 2 Upgrades ground combat rating