There are 10 environmental classes of planets in Master of Orion II. They range from barely supportive of life to natural havens where organisms can thrive with abundance. The environmental classification effects the food production, and maximum population of a planet. The mineral richness also varies from planet to planet. Some are pitiful in the resources they provide for manufacturing, while others provide significant bonuses to industrial production. The size of these planets also varies. The classes are tiny, small, medium, large, & huge. This factor effects the maximum population limit as well. The strength of gravity on planets can vary, giving bonuses or penalties to inhabitants, depending on how they evolved. There is also a wide variety of special attributes that can be found in star systems and planets.


This class of planet is the least hospitable to life. No farming is permitted on this environment (unless Biomorphic Fungi is researched). Typically, these planets will have greater mineral abundance than those highly supportive of life. There is also a maintenance fee penalty of 50% due to the harsh environment causing more rapid deterioration of structures. The base properties of these planets are as follows:

Food per Farmer: 0
Maximum Population per Size Class: 1, 3, 4, 5, 6
Maintenance Penalty: 50%

This class of planet is the second-least hospitable to life. No farming is permitted on this environment (unless Biomorphic Fungi is researched). If a planetary shield is constructed, the environmantal class will change to barren. Typically, these planets will have greater mineral abundance than those highly supportive of life, part of the mineral/hospitability tradeoff. There is also a maintenance fee penalty of 25% due to the harsh environment causing more structural deterioration. The base properties of these planets are as follows:

Food per Farmer: 0
Maximum Population per Size Class: 1, 3, 4, 5, 6
Maintenance Penalty: 25%

Barren planets still do not allow for food production, unless one has reasearched the proper technologies. They do not impose any maintenance or worker penalties. Generally, these planets will be found with the mineral class of "Abundant." Since they are not as hostile of environments, they will not have the same mineral bonuses. The base properties of these planets are as follows:

Food per Farmer: 0
Maximum Population per Size Class: 1, 3, 4, 5, 6
Maintenance Penalty: 0%

Desert planets will support food production at their base level. They also have a 25% maintenance penalty, due to the harsh, dry environment. Generally, these planets will be found with the mineral class of "Abundant." The base properties of these planets are as follows:

Food per Farmer: 1
Maximum Population per Size Class: 1, 3, 4, 5, 6
Maintenance Penalty: 25%

Tundra planets are frigid places, but will still support farming. There is no maintenance penalty, either. Their mineral abundance is usually "Abundant," and very rarely greater than that. The base properties of these planets are as follows:

Food per Farmer: 1
Maximum Population per Size Class: 1, 3, 4, 5, 6
Maintenance Penalty: 0%

Ocean-class planets are more supportive of life than the aforementioned classes. They allow for greater food production from farmers, and still no penalties. Aquatic races treat these planets as Gaia environments, giving them a bonus. These worlds are generally Abundant in minerals, seldom more. The base properties of these planets are as follows:

Food per Farmer: 2
Maximum Population per Size Class: 1, 3, 4, 5, 6
Maintenance Penalty: 0%

Swamp planets are similar in hospitability to Ocean worlds, but have a greater population limit. Again, there are no maintenance penalties on these worlds. The base properties of these planets are as follows:

Food per Farmer: 2
Maximum Population per Size Class: 2, 4, 6, 8, 10
Maintenance Penalty: 0%

While Arid plants only allow for 1 food unit per farmer, they have a further elevated population limit. This can be an advantage to production and research, provided there are sufficient freighters or food technologies to make up for the farming penalty. The base properties of these planets are as follows:

Food per Farmer: 1
Maximum Population per Size Class: 3, 6, 9, 12, 15
Maintenance Penalty: 0%

These planets are of the most desirable for colonization. They have a much greater population limit than previous classes, and allow for more food production. They are usually mineral "Abundant" as well. The base properties of these planets are as follows:

Food per Farmer: 2
Maximum Population per Size Class: 4, 8, 12, 16, 20
Maintenance Penalty: 0%

Gaia planets are the most sought-after class. They give maximum food production, as well as the greatest population allowance. There are no penalties associated with them, unless the gravity level is "offensive" to one's race. These planets are usually guarded by space monsters, and can have bonuses. The base properties of these planets are as follows:

Food per Farmer: 3
Maximum Population per Size Class: 5, 10, 15, 20, 25
Maintenance Penalty: 0%