Planets come in 4 sizes (Small, Medium, Large, and Huge). Gas Giants are technically considered Giant, but you can’t colonize them. Unlike previous MOO games, there currently are not any Tiny planet sizes.

Planet size cannot be changed though there is a complicated workaround if you destroy a planet with a Stellar Converter [Temporal Physics, Tier 11] and then construct an artificial planet out of the resulting asteroid fragments.

Planet size determines the upper population limit and the maximum number of possible farming and mining slots available, though biome determines the number of workable slots and the actual population limit. Planet size combined with biome also determines the value of each slot, as well as the planet's pollution tolerance. See Section 7 for more details.

There are 11 different types of biomes you can naturally encounter, along with 4 Uber Biomes, plus asteroid belts and gas giants.

• Volcanic planets cannot normally be changed to another biome. The one exception is the Silicoids, who have the Inferno Uber Biome ability which lets them convert Volcanic planets into Inferno with [Xenobiotics, Tier 3].
  
  
• Toxic planets become Barren with a Toxic Processor [Xenobiotics, Tier 3]. If the now Barren planet loses the Toxic Processor it goes back to being Toxic. But if the Barren planet is terraformed it does not revert to Toxic if it later loses the Toxic Processor.
  
  
• Radiated planets become Barren with a Planetary Radiation Shield [Magneto Gravitics, Tier 5], Planetary Flux Shield [Quantum Field, Tier 10], or Planetary Barrier Shield [Temporal Fields, Tier 12]. If the now Barren planet loses the Planetary Shield it goes back to being Radiated. But if the Barren planet is terraformed it does not revert to Radiated if it later loses the Planetary Shield.
  
  
• Barren planets become either Desert or Tundra with Terraforming [Genetic Mutations, Tier 4]. This determination is sometimes random and sometimes fixed. There has been mention that the orbital position of the planet determines whether it follows a dry path, a wet path, or is randomly determined between the two.
  
  
• Desert planets become Arid with Terraforming [Genetic Mutations, Tier 4]. The Mrrshan have the Grasslands Uber Biome ability which lets them convert Desert planets into Grasslands with [Xenobiotics, Tier 3].
  
  
• Tundra planets become Swamp with Terraforming [Genetic Mutations, Tier 4].
  
  
• Arid planets become Terran with Terraforming [Genetic Mutations, Tier 4]. The Klackon have the Cavernous Uber Biome ability which lets them convert Arid planets into Cavernous with [Xenobiotics, Tier 3].
  
  
• Swamp planets become Terran (not Ocean) with Terraforming [Genetic Mutations, Tier 4]. The Sakkra have the Tropical Uber Biome ability which lets them convert Swamp planets into Tropical with [Xenobiotics, Tier 3].
  
  
• Ocean planets are ranked as the same level as Terran, but right now they can be Terraformed [Genetic Mutations, Tier 4] into Terran.
  
  
• Terran planets become Gaia with Gaia Transformation [Trans Genetics, Tier 7].
  
  
• Gaia planets are at the top tier of biomes (now much better than Uber planets in EA3).
  
  
• The four Uber Biomes are Tropical (Swamp), Grasslands (Desert), Cavernous (Arid), and Inferno (Volcanic) and require [Xenobiotics, Tier 3] to transform. Originally the Uber Biomes were competitive with Gaia, then they were changed to be equivalent to Terran, and now they are midway between Terran and Gaia. They can be transformed into into Gaia with [Trans Genetics, Tier 7].
  
  If you are interested in Uber Planets, feel free to check out my guide:
  http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=637440060
  
• Asteroid Belts and Gas Giants can be converted into Large or Huge Barren planets with Gas Giant Compression or Artificial Planet Construction [both Planetology, Tier 5] by using a Space Factory (unlike MOO2, you do not need a colony in that system). Alternatively, you can use a Space Factory to build a Superscalar Gas Harvester (+1 credit) on a Gas Giant, or an Asteroid Mine (+2 credits) or an Asteroid Laboratory (+2 research, 2 maintenance) on an Asteroid Belt.

Technically, you can destroy a planet with a Stellar Converter [Temporal Physics, Tier 11] and then convert the Asteroid Belt into a Large or Huge Barren planet. This is one way to essentially “terraform” a Volcanic planet.

If a planet reaches 100% pollution this will degrade its biome and pollution is reset to 0%:

• Gaia planets degrade to Terran.
  
• Terran degrades to either Arid or Swamp (possibly depends on the orbit).
  
• Ocean degrades to Tundra.
  
• Arid degrades to Desert.
  
• Swamp degrades to Tundra.
  
• Desert and Tundra degrade to Barren.

Biome determines the number of available farming and mining slots (out of the maximum which is determined by planet size). Biome combined with planet size determines the value of farming slots and the pollution tolerance of the planet. See Section 7 for more details.

There are a few colony structures that are limited to specific biomes:

• Deep Sea Cooling, +3 research [Cybertronics, Tier 6] (only Swamp, Ocean, Terran, Gaia).
  
• Soil Enrichment Facility, farmers produce +1 food [Xenobiotics, Tier 3] (Any biome that is not Toxic, Radiated, or Volcanic).
  
• Fungal Farms, +1 food [Deep Space Exploration, Tier 2] (only Radiated, Toxic, Barren, Desert, Tundra); In older versions, Fungal Farms produced +2 food instead of +1..

The Wiki mentions additional biome-restricted structures like: Radiotelescopic Observatory (Radiated), Anaerobic Colonies (Barren), Underground Storage (Tundra), High Orbit Sonar (Ocean), and Solar Kiln (Desert & Grasslands). However, none of these are currently implemented.

Also note that if the biome changes, you lose any structures that are no longer compatible with the new biome. So if your Desert planet has Fungal Farms and you terraform it into Arid, you will lose the Fungal Farms. In some cases, it might take a turn for the structure to disappear.

There are 5 categories of mineral richness (Ultra Poor, Poor, Abundant, Rich, Ultra Rich).

Mineral richness cannot normally be changed although there are rare GNN events that may increase the mineral level of a random planet. In earlier MOO games, there was also a random event that could decrease the mineral level of a random planet but I have not seen that happen yet after multiple playthroughs of the new MOO.

Mineral richness combined with planet size determines the value of mining slots. See Section 7 for more details.

There is one colony structure, Crust Prospecting [Private Funding, Tier 3], which provides a flat +2 production and can only be built on Ultra Poor or Poor planets.

Planets can have Low, Normal, or High Gravity.

Most races suffer a -50% food and production penalty on High Gravity or Low Gravity planets. This penalty only affects the output of farmers and workers and does not affect any food or hammers generated by buildings or resources.

The Bulrathi have a racial trait so they do not suffer this penalty on High Gravity planets while the Psilon have a racial trait so they do not suffer this penalty on Low Gravity planets. Note that the racial trait applies to citizens of the race not to the Empire as a whole.

In prior MOO games, Low Gravity was a racial disadvantage. It meant you would treat Low-G worlds as normal but suffer penalties on Normal-G and High-G worlds. In this version of the game, Low-G is an advantage. You suffer no penalties on Low-G or Normal-G worlds.

Gravity Generators [Gravitic Field, Tier 6] are a colony structure that eliminates gravity penalties.

Right now, if you make a custom race and select Large Homeworld and Ultra Rich Homeworld, your homeworld will automatically be High-G. You will also get a High-G world if you select a Huge Homeworld and either a Rich or Ultra Rich Homeworld.

Some planets contain resources which provide additional bonuses:

• Gold and Gems are functionally equivalent. They give the colony a flat +2 credit bonus. Depending on your tax level, an average citizen probably yields 2 or 3 credits each, so you can think of Gold/Gems as providing the income of an additional citizen.
  
  
• Red Fungus and Seagrass are functionally equivalent. They give the colony a flat +2 food bonus. In Early Access, the food bonus does not appear on the list of calculations but it is factored into the end result. You can think of Red Fungus/Seagrass as being a free Hydroponics Farm that you automatically get when you colonize.
  
  
• Dark Quartz gives the colony a flat +2 production bonus. In Early Access, the production bonus does not appear on the list of calculations but it is factored into the end result. You can think of Dark Quartz as being a free Automated Factory that you automatically get when you colonize.
  
  
• Artifacts give the colony a flat +2 research bonus. You can think of Artifacts as being a free Research Laboratory that you automatically get when you colonize.
  
  
• The previews indicate plans to have strategic resources that may reduce the production costs of ships, be tradable through diplomacy, or may be the goals of independent planet quests. However, these are not currently implemented in Early Access.
  
  
• The Orion planet does not currently have a special. This is in contrast with past MOO games where Orion had a souped up version of Artifacts.

Some planets have moons.

Moons allow you to build two special colony structures [both Artificial Laboratory, Tier 4]. The Moon Laboratory provides +4 research while the Orbital Shipyard reduces ship costs by 20%.

Since Gas Giants do not have moons, when exploring you know that any Huge planet with moons is not a Gas Giant.

Next we will talk about the game mechanics for the various planetary types. Due to word limits, I have to break this up into three different sections. We will start by discussing population size and science slots:

A. Population Size
B. Science Slots


A. Population Size

The upper limit for population size is determined by the size of the planet but is modified by the available farming and mining cells (which are determined by biome). Note that EA3 increased the size for all planets by 4, adding 2 farming and 2 mining slots.

• The maximum size for Small planets is a population of 12 (6 farming slots, 6 mining slots).
  
• The maximum size for Medium planets is a population of 16 (8 farming slots, 8 mining slots).
  
• The maximum size for Large planets is a population of 20 (10 farming slots, 10 mining slots).
  
• The maximum size for Huge planets is a population of 24 (12 farming slots, 12 mining slots).

Gaia planets have all farming and mining slots available so the maximum population for a Large Gaia planet is 20. In contrast, a Large Desert planet will have 5 farming slots available (5 closed) and 7 mining slots available (3 closed) so its maximum population is 12.

There are is currently one technology that may increase the population size of a planet:

• Advanced City Planning [Galactic Economics, Tier 9] increases the maximum size of all planets by 5 but does not create or open up any new farming or mining slots, despite what the description says
  
  
• EA1, EA2, and EA3 had a technology, Biomorphic Fungi [previously Astro Biology, Tier 6], which opend up any closed farming slots, increasing population size for most biomes. However, it has been removed in EA4.

Here is a list of maximum population sizes:

• Small Gaia & Tropical/Cavernous/Grasslands: 12 max pop
  
• Small Terran: 10
  
• Small Ocean, Arid, & Swamp: 9
  
• Small Tundra & Desert: 7
  
• Small Barren & Inferno: 6
  
• Small Toxic, Radiated, & Volcanic: 4
  
  
• Medium Gaia & Tropical/Cavernous/Grasslands: 16
  
• Medium Terran: 13
  
• Medium Swamp: 12
  
• Medium Ocean & Arid: 11
  
• Medium Tundra: 10
  
• Medium Desert: 9
  
• Medium Barren & Inferno: 8
  
• Medium Toxic, Radiated, & Volcanic: 5
  
  
• Large Gaia & Tropical/Cavernous/Grasslands: 20
  
• Large Terran: 16
  
• Large Ocean: 15
  
• Large Swamp: 14
  
• Large Arid: 13
  
• Large Tundra & Desert: 12
  
• Large Barren & Inferno: 10
  
• Large Volcanic: 7
  
• Large Toxic & Radiated: 6
  
  
• Huge Gaia & Tropical/Cavernous/Grasslands: 24
  
• Huge Terran: 19
  
• Huge Ocean & Swamp: 17
  
• Huge Arid: 16
  *] Huge Tundra: 14
  
• Huge Desert: 13
  
• Huge Inferno: 12
  
• Huge Barren: 11
  
• Huge Volcanic: 8
  
• Huge Toxic & Radiated: 7

B. Science Slots

All planets can have an unlimited number of scientist slots.

The number of slots visually displayed is equal to your current population. So if you have a new colony with population 1, only a single scientist slot is shown. But when you increase in population, new scientists slots will be added automatically.

The default yield for each scientist is 1 research. This can be increased with two colony structures:

• Advanced Data Center [Private Funding, Tier 3] increases the yield of each scientist by 1.
  
• Astro University [Teaching Methods, Tier 6] increases the yield of each scientist by 2.

Psilon scientists get a +50% yield bonus. Sakkra and Silicoid scientists get a -25% yield penalty. Aliens who have yet been assimilated get a -50% yield.

This is an analysis of the number and value of farming slots:

C. Farming Slots

C. Farming Slots

The planet size determines the maximum number of potential farming slots but the biome determines how many of those are farmable.

In addition, both planet size and biome determine the base values of each farming slot.

Here is a listing of farming values for the various planet sizes and types (numbers in parentheses are closed off are not currently accessible since Biomorphic Fungi has been removed):

• Small Gaia
  5-5-4-4-3-3 [Public Release]
  5-4-3-3-3-3 [EA4]
  5-4-4-3-3-2 [EA3]
  4-4-3-3 [EA1 & EA2]
  
  
• Small Tropical/Cavernous/Grasslands
  5-4-3-3-3-3 [Public Release]
  4-4-3-3-2-2 [EA4]
  4-3-3-2-2-(1) [EA3]
  4-4-3-3 [EA1 & EA2]
  
  
• Small Terran
  4-4-3-3-2-(2) [Public Release]
  4-3-2-2-2-(2) [EA4]
  4-3-3-2-2-(1) [EA3]
  4-3-3-2 [EA1 & EA2]
  
  
• Small Ocean
  4-3-2-2-2-(2) [Public Release]
  3-3-2-2-(2-2) [EA4]
  4-3-2-2-(2-1) [EA3]
  4-3-3-(2) [EA1 & EA2]
  
  
• Small Swamp
  3-3-2-2-(1-1) [Public Release]
  3-3-2-2-2-(2) [EA4]
  4-3-2-2-2-(1) [EA3]
  3-3-2-(2) [EA1 & EA2]
  
  
• Small Arid
  3-2-2-1-(1-1) [Public Release, EA4, & EA3]
  3-2-2-(1) [EA1 & EA2]
  
  
• Small Tundra
  3-2-1-(1-1-1) [Public Release, EA4 & EA3]
  2-2-(1-1) [EA1 & EA2]
  
  
• Small Desert
  2-1-1-(1-1-1) [Public Release, EA4 & EA3]
  2-1-(1-1) [EA1 & EA2]
  
  
• Small Barren
  1-1-(1-1-1-1) [Public Release]
  2-(1-1-1-1-1) [EA4 & EA3]
  2-1-(1-1) [EA1 & EA2]
  
  
• Small Toxic, Radiated, Volcanic, & Inferno
  (0-0-0-0-0-0) [Public Release, EA4 & EA3]
  (0-0-0-0) [EA1 & EA2]
  
  
• Medium Gaia
  5-5-4-4-4-4-3-3 [Public Release]
  5-4-4-3-3-3-3-3 [EA4]
  5-4-4-4-3-3-3-2 [EA3]
  5-4-4-3-3-2 [EA1 & EA2]
  
  
• Medium Tropical/Cavernous/Grasslands
  5-4-4-3-3-3-3-3 [Public Release]
  4-4-3-3-3-3-2-2 [EA4]
  4-3-3-3-2-2-2-(1) [EA3]
  5-4-4-3-3-(2) [EA1 & EA2]
  
  
• Medium Terran
  4-4-3-3-3-3-(2-2) [Public Release]
  4-3-3-2-2-2-2-(1) [EA4]
  4-3-3-3-2-2-2-(1) [EA3]
  4-4-3-3-2-(2) [EA1 & EA2]
  
  
• Medium Ocean
  4-3-3-2-2-2-(2-2) [Public Release]
  3-3-3-2-2-2-(2-1) [EA4]
  4-3-3-2-2-2-(1-1) [EA3]
  4-3-3-3-2-(2) [EA1 & EA2]
  
  
• Medium Swamp
  3-3-2-2-2-2-(1-1) [Public Release]
  3-3-3-2-2-2-(2-1) [EA4]
  4-3-3-2-2-2-(1-1) [EA3]
  4-3-2-2-(2-1) [EA1 & EA2]
  
  
• Medium Arid
  3-2-2-2-1-(1-1-1) [Public Release, EA4, & EA3]
  3-2-2-2-(1-1) [EA1 & EA2]
  
  
• Medium Tundra
  3-2-1-1-(1-1-1-1) [Public Release, EA4, & EA3]
  3-2-1-(1-1-1) [EA1 & EA2]
  
  
• Medium Desert
  2-2-1-1-(1-1-1-1) [Public Release, EA4, & EA3]
  2-1-1-(1-1-1) [EA1 & EA2]
  
  
• Medium Barren
  1-1-1-(1-1-1-1-1) [Public Release]
  2-(1-1-1-1-1-1-1) [EA4 & EA3]
  2-1-1-(1-1-1) [EA1 & EA2]
  
  
• Medium Toxic, Radiated, Volcanic, & Inferno
  (0-0-0-0-0-0-0-0) [Public Release, EA4, & EA3]
  (0-0-0-0-0-0) [EA1 & EA2]
  
  
• Large Gaia
  5-5-5-4-4-4-4-3-3-3 [Public Release]
  5-4-4-4-3-3-3-3-3-3 [EA4]
  5-5-4-4-4-3-3-3-2-2 [EA3]
  5-4-4-4-3-3-3-2 [EA1 & EA2]
  
  
• Large Tropical/Cavernous/Grasslands
  5-4-4-4-3-3-3-3-3-3 [Public Release]
  4-4-4-3-3-3-3-2-2-2 [EA4]
  5-4-3-3-2-2-2-2-1-(1) [EA3]
  5-4-4-4-3-3-3-(2) [EA1 & EA2]
  
  
• Large Terran
  4-4-4-3-3-3-3-2-2-(2) [Public Release]
  4-3-3-3-2-2-2-2-2-(2) [EA4]
  5-4-3-3-2-2-2-2-1-(1) [EA3]
  5-4-3-3-3-2-2-(2) [EA1 & EA2]
  
  
• Large Ocean
  4-3-3-3-2-2-2-2-(2-2) [Public Release]
  3-3-3-3-2-2-2-(2-2-1) [EA4]
  4-4-3-3-2-2-2-(1-1-1) [EA3]
  5-4-3-3-2-2-(2-2) [EA1 & EA2]
  
  
• Large Swamp
  3-3-3-2-2-2-2-(1-1-1) [Public Release]
  3-3-3-3-2-2-2-2-(2-1) [EA4]
  4-4-3-3-2-2-2-1-(1-1) [EA3]
  4-3-3-2-2-(2-2-1) [EA1 & EA2]
  
  
• Large Arid
  3-3-2-2-2-1-(1-1-1-1) [Public Release & EA4]
  4-3-2-2-1-1-(1-1-1-1) [EA3]
  4-3-2-2-1-(1-1-1) [EA1 & EA2]
  
  
• Large Tundra
  3-2-2-1-1-(1-1-1-1-1) [Public Release, EA4, & EA3]
  3-2-2-1-(1-1-1-1) [EA1 & EA2]
  
  
• Large Desert
  2-2-1-1-1-(1-1-1-1-1) [Public Release, EA4, & EA3]
  2-1-1-1-(1-1-1-1) [EA1 & EA2]
  
  
• Large Barren
  1-1-1-1-(1-1-1-1-1-1) [Public Release]
  2-2-(1-1-1-1-1-1-1-1) [EA4 & EA3]
  2-1-1-(1-1-1-1-1) [EA1 & EA2]
  
  
• Large Toxic, Radiated, Volcanic, & Inferno
  (0-0-0-0-0-0-0-0-0-0) [Public Release, EA4, & EA3]
  (0-0-0-0-0-0-0-0) [EA1 & EA2]
  
  
• Huge Gaia
  5-5-5-5-4-4-4-4-3-3-3-3 [Public Release]
  5-4-4-4-4-3-3-3-3-3-3-3 [EA4]
  ??? [EA3]
  5-5-4-4-4-3-3-3-2-2 [EA1 & EA2]
  
  
• Huge Tropical/Cavernous/Grasslands
  5-4-4-4-4-3-3-3-3-3-3-3 [Public Release]
  4-4-4-4-3-3-3-3-2-2-2-2 [EA4]
  5-4-4-3-3-2-2-2-2-1-(1-1) [EA3]
  5-5-4-4-4-3-3-3-2-(2) [EA1 & EA2]
  
  
• Huge Terran
  4-4-4-4-3-3-3-3-2-2-(2-2) [Public Release]
  4-3-3-3-3-2-2-2-2-2-(1-1) [EA4]
  5-4-4-3-3-2-2-2-2-1-(1-1) [EA3]
  5-4-4-3-3-3-2-2-2-(2) [EA1 & EA2]
  
  
• Huge Ocean
  4-3-3-3-3-2-2-2-2-(2-2-2) [Public Release]
  3-3-3-3-3-2-2-2-(2-2-1-1) [EA4]
  5-4-3-3-2-2-2-2-(1-1-1-1) [EA3]
  5-4-4-3-3-2-2-2-(?-?) [EA1 & EA2]
  
  
• Huge Swamp
  3-3-3-3-2-2-2-2-(1-1-1-1) [Public Release]
  3-3-3-3-3-2-2-2-2-(2-1-1) [EA4]
  ??? [EA3]
  4-4-3-3-2-2-2-(1-1-1) [EA1 & EA2]
  
  
• Huge Arid
  3-3-2-2-2-2-1-(1-1-1-1-1) [Public Release & EA4]
  4-3-2-2-2-1-1-(1-1-1-1-1) [EA3]
  4-3-2-2-2-1-1-(1-1-1) [EA1 & EA2]
  
  
• Huge Tundra
  3-2-2-2-1-1-(1-1-1-1-1-1) [Public Release & EA4]
  3-2-2-2-1-1-(1-1-1-1-1-1) [EA3]
  3-2-2-1-1-(1-1-1-1-1) [EA1 & EA2]
  
  
• Huge Desert
  2-2-1-1-1-(1-1-1-1-1-1-1) [Public Release, EA4, & EA3]
  2-2-1-1-1-(1-1-1-1-1) [EA1 & EA2]
  
  
• Huge Barren
  1-1-1-1-1-1-(1-1-1-1-1-1) [Public Release]
  2-2-(1-1-1-1-1-1-1-1-1-1) [EA4 & EA3]
  2-2-1-1-(1-1-1-1-1-1) [EA1 & EA2]
  
  
• Huge Toxic, Radiated, Volcanic, & Inferno
  (0-0-0-0-0-0-0-0-0-0-0-0) [Public Release, EA4, & EA3]
  (0-0-0-0-0-0-0-0-0-0) [EA1 & EA2]

These farming yields can be increased with two colony structures:

• Soil Enrichment Facility [Xenobiotics, Tier 3] increases the yield of each farmer by 1.
  
• Subterranean Farms [previously Planetology, Tier 5, now Astro Biology] increases the yield of each farmer by 1.

Klackon farmers get a +50% yield. Silicoid farmers do not generate food. Aliens who have yet been assimilated get a -50% yield. Races on the wrong type of Gravity world get a -50% yield.

This is the third part of the game mechanics where we discuss the number and value of mining slots, as well as pollution and some game calculations:

D. Mining Slots
E. Pollution
F. Game Calculations


D. Mining Slots

The planet size determines the maximum number of potential mining slots.

The planet size and mineral richness determine the exact value of each slot, which is the same for all planets of a given size.

However, the biome determines how many of those slots are actually mineable. There is no way to open up closed slots because there is no mining equivalent to Biomorphic Fungi.

For Small planets, the distributions are:

• 1-1-1-1-1-1 (Ultra Poor)
  
• 2-2-1-1-1-1 (Poor)
  
• 3-2-2-1-1-1 (Abundant)
  
• 3-3-2-2-2-2 (Rich) [Public Release & EA4]
  
• 4-4-3-3-3-3 (Ultra Rich) [Public Release & EA4]
  
  
• 4-3-2-2-2-1 (Rich) [EA3]
  
• 5-4-3-3-3-2 (Ultra Rich) [EA3]
  
  For EA1 & EA2 the values were:
  
  
• 1-1-1-1 (Ultra Poor)
  
• 2-2-1-1 (Poor)
  
• 3-2-2-1 (Abundant)
  
• 3-3-2-2 (Rich)
  
• 4-4-3-3 (Ultra Rich)

For Medium planets, the distributions are:

• 1-1-1-1-1-1-1-1 (Ultra Poor)
  
• 2-2-1-1-1-1-1-1 (Poor)
  
• 3-2-2-2-1-1-1-1 (Abundant)
  
• 3-3-3-2-2-2-2-2 (Rich) [Public Release & EA4]
  
• 4-4-4-3-3-3-3-3 (Ultra Rich) [Public Release & EA4]
  
  
• 4-3-3-2-2-2-2-1 (Rich) [EA3]
  
• 5-4-4-3-3-3-3-2 (Ultra Rich) [EA3]
  
  For EA1 & EA2 the values were:
  
  
• 1-1-1-1-1-1 (Ultra Poor)
  
• 2-2-1-1-1-1 (Poor)
  
• 3-2-2-2-1-1 (Abundant)
  
• 4-3-3-2-2-1 (Rich)
  
• 5-4-4-3-3-2 (Ultra Rich)

For Large planets, the distributions are:

• 1-1-1-1-1-1-1-1-1-1 (Ultra Poor)
  
• 3-2-1-1-1-1-1-1-1-1 (Poor)
  
• 3-3-2-2-2-1-1-1-1-1 (Abundant) [Public Release & EA4]
  
• 3-3-3-3-2-2-2-2-2-1 (Rich) [Public Release & EA4]
  
• 4-4-4-4-3-3-3-3-3-2 (Ultra Rich) [Public Release & EA4]
  
  
• 4-3-2-2-1-1-1-1-1-1 (Abundant) [EA3]
  
• 4-4-3-3-2-2-2-1-1-1 (Rich) [EA3]
  
• 5-5-4-4-3-3-3-2-2-2 (Ultra Rich) [EA3]
  
  For EA1 & EA2 the values were:
  
  
• 1-1-1-1-1-1-1-1 (Ultra Poor)
  
• 3-2-1-1-1-1-1-1 (Poor)
  
• 4-3-2-2-1-1-1-1 (Abundant)
  
• 4-3-3-3-2-2-2-1 (Rich)
  
• 5-4-4-4-3-3-3-2 (Ultra Rich)

For Huge planets, the distributions are:

• 1-1-1-1-1-1-1-1-1-1-1-1 (Ultra Poor)
  
• 3-2-1-1-1-1-1-1-1-1-1-1 (Poor)
  
• 3-3-2-2-2-2-1-1-1-1-1-1 (Abundant) [Public Release & EA4]
  
• 3-3-3-3-3-2-2-2-2-2-2-1 (Rich) [Public Release & EA4]
  
• 4-4-4-4-4-3-3-3-3-3-3-2 (Ultra Rich) [Public Release & EA4]
  
  
• 4-3-2-2-2-1-1-1-1-1-1-1 (Abundant) [EA3]
  
• 5-4-3-3-3-2-2-2-1-1-1-1 (Rich) [EA3]
  
• 5-5-4-4-4-3-3-3-3-2-2-2 (Ultra Rich) [EA3]
  
  For EA1 & EA2 the values were:
  
  
• 1-1-1-1-1-1-1-1-1-1 (Ultra Poor)
  
• 3-2-1-1-1-1-1-1-1-1 (Poor)
  
• 4-3-2-2-2-1-1-1-1-1 (Abundant)
  
• 5-4-3-3-2-2-2-2-?-? (Rich)
  
• 5-5-4-4-4-3-3-3-2-2 (Ultra Rich)

So for Small Abundant planets you would have the following for different biomes:

• 3-2-2-1-1-1 (Gaia, Tropical/Cavernous/Grasslands, Inferno)
  
• 3-2-2-1-1-(1) (Terran, Swamp, & Arid)
  
• 3-2-2-1-(1-1) (Ocean, Tundra, Desert, Barren, Toxic, Radiated, & Volcanic)

So for Medium Abundant planets you would have the following for different biomes:

• 3-2-2-2-1-1-1-1 (Gaia, Tropical/Cavernous/Grasslands, Inferno)
  
• 3-2-2-2-1-1-1-(1) (Terran)
  
• 3-2-2-2-1-1-(1-1) (Swamp, Arid, & Tundra)
  
• 3-2-2-2-1-(1-1-1) (Ocean, Desert, Bareen, Toxic, Radiated, & Volcanic)

So for Large Abundant planets you would have the following for different biomes:

• 3-3-2-2-2-1-1-1-1-1 (Gaia, Tropical/Cavernous/Grasslands, Inferno)
  
• 3-3-2-2-2-1-1-(1-1-1) (Terran, Ocean, Swamp, Arid, Tundra, Desert, Volcanic)
  
• 3-3-2-2-2-1-(1-1-1-1) (Barren, Toxic, Radiated)

So for Huge Abundant planets you would have the following for different biomes:

• 3-3-2-2-2-2-1-1-1-1-1-1 (Gaia, Tropical/Cavernous/Grasslands, Inferno)
  
• 3-3-2-2-2-2-1-1-1-(1-1-1) (Terran, Swamp, Arid)
  
• 3-3-2-2-2-2-1-1-(1-1-1-1) (Ocean, Tundra, Desert, Volcanic)
  
• 3-3-2-2-2-2-1-(1-1-1-1-1) (Barren, Toxic, Radiated)

These mining yields can be increased with three colony structures:

• Neutron Collider [Neutrino Physics, Tier 3] increases the yield of each worker by 1.
  
• Robo-Miners [Cybertechnics, Tier 5] increases the yield of each worker by 1.
  
• Deep Core Mining [Tectonic Engineering, Tier 9] increases the yield of each worker by 2.

Klackon and Meklar workers get a +25% yield. Aliens who have yet been assimilated get a -50% yield. Races on the wrong type of Gravity world get a -50% yield.


E. Pollution

* These values are from EA3.

Each biome also has a natural tolerance for pollution which translates to an inherent –X% a turn (the amount also varies based on planet size). Radiated, Toxic, and Volcanic planets are essentially immune to pollution. They have a sufficiently large –X% that pollution will never accumulate to 100%. The relative sensitivity is:

Toxic & Radiated & Volcanic (immune) > Desert & Barren > Arid > Swamp & Tundra > Tropical/Cavernous/Grasslands & Terran > Ocean > Gaia (most sensitive)

If you Terraform or Gaia Transform a planet, the pollution is reset to 0. If you Uber Transform a planet, the pollution is not reset. Pollution will also gradually decrease while in the process of terraforming or transforming.

Additionally, you can actively clean up pollution by choosing that project from the production list.

If you settle a new colony, at 1 production, the planets would have the following natural pollution rates:

• Small Toxic, Radiated, & Volcanic: -100%
  
• Small Desert & Barren: -8%
  
• Small Arid: -4%
  
• Small Swamp & Tundra: -4%
  
• Small Tropical/Cavernous/Grasslands & Terran: -4%
  
• Small Ocean: -3%
  
• Small Gaia: -2%
  
  
• Medium Toxic, Radiated, & Volcanic: -66%
  
• Medium Desert & Barren: -5%
  
• Medium Arid: -3%
  
• Medium Swamp & Tundra: -3%
  
• Medium Tropical/Cavernous/Grasslands & Terran: -2%
  
• Medium Ocean: -2%
  
  
• Large Toxic, Radiated, & Volcanic: -40%
  
• Large Desert & Barren: -3%
  
• Large Arid: -2%
  
• Large Swamp & Tundra: -2%
  
• Large Tropical/Cavernous/Grasslands & Terran: -1%
  
• Large Ocean: -1%
  
• Large Gaia: -1%
  
  
• Huge Toxic, Radiated, & Volcanic: -25%
  
• Huge Desert & Barren: -2%
  
• Huge Arid: -1%
  
• Huge Swamp & Tundra: -1%
  
• Huge Tropical/Cavernous/Grasslands & Terran: -1%
  
• Huge Ocean: -1%
  
• Huge Gaia: -1%

F. Game Calculations

If you look at the Master of Orion wiki, its Biome section gives a few game stats:

• "Base Food per Cell" translates to the value of each farming slot.
  
  
• "Farmable Cells" and "Productive Cells" translates to the number of available slots. The equation seems to be (% of cells) * (maximum number of cells for that planet size), then round up to the nearest integer. This seems to work out for the majority of calculations.
  
  
• "Pollution absorption" gives the relative values of pollution tolerance. Although the wiki says that Swamp & Tundra have the same value and Desert & Barren have the same value, I have seen some slight variation.

* This is some data from EA4:

• EA1, EA2, and EA3 had a technology, Biomorphic Fungi [previously Astro Biology, Tier 6], which opend up any closed farming slots, increasing population size for most biomes. However, it has been removed in EA4.

Here is a list of maximum population sizes:

• Small Gaia & Tropical/Cavernous/Grasslands: 12 max pop
  
• Terran: 10
  
• Small Ocean, Arid, & Swamp: 9
  
• Small Tundra & Desert: 7
  
• Small Barren, Toxic, Radiated, & Volcanic: 4
  
  
• Medium Gaia & Tropical/Cavernous/Grasslands: 16
  
• Medium Terran: 14
  
• Medium Ocean: 12
  
• Medium Arid & Swamp: 11
  
• Medium Tundra: 10
  
• Medium Desert: 9
  
• Medium Barren, Toxic, Radiated, & Volcanic: 5
  
  
• Large Gaia & Tropical/Cavernous/Grasslands: 20
  
• Large Terran: 18
  
• Large Swamp: 15
  
• Large Ocean: 14
  
• Large Arid: 13
  
• Large Tundra & Desert: 12
  
• Large Barren & Volcanic: 7
  
• Large Toxic & Radiated: 6
  
  
• Huge Gaia & Tropical/Cavernous/Grasslands: 24
  
• Huge Terran: 20
  
• Huge Ocean & Swamp: 17
  
• Huge Arid: 16
  *] Huge Tundra: 14
  
• Huge Desert: 13
  
• Huge Barren & Volcanic: 8
  
• Huge Toxic & Radiated: 7

So for Small Abundant planets you would have the following for different biomes:

• 3-2-2-1-1-1 (Gaia, Tropical/Cavernous/Grasslands)
  
• 3-2-2-1-1-(1) (Terran, Ocean, Arid)
  
• 3-2-2-1-(1-1) (Swamp, Tundra, Desert, Toxic, Radiated, Volcanic)
  
• 3-2-2-(1-1-1) (Barren)

So for Medium Abundant planets you would have the following for different biomes:

• 3-2-2-2-1-1-1-1 (Gaia, Tropical/Cavernous/Grasslands)
  
• 3-2-2-2-1-1-1-(1) (Terran)
  
• 3-2-2-2-1-1-(1-1) (Ocean, Arid, Tundra)
  
• 3-2-2-2-1-(1-1-1) (Swamp, Desert, Toxic, Radiated, Volcanic)
  
• 3-2-2-2-(1-1-1-1) (Barren)

So for Large Abundant planets you would have the following for different biomes:

• 3-3-2-2-2-1-1-1-1-1 (Gaia, Tropical/Cavernous/Grasslands)
  
• 3-3-2-2-2-1-1-1-1-(1) (Terran)
  
• 3-3-2-2-2-1-1-(1-1-1) (Ocean, Swamp, Arid, Tundra, Desert, Volcanic)
  
• 3-3-2-2-2-1-(1-1-1-1) (Toxic, Radiated)
  
• 3-3-2-2-2-(1-1-1-1-1) (Barren)

So for Huge Abundant planets you would have the following for different biomes:

• 3-3-2-2-2-2-1-1-1-1-1-1 (Gaia, Tropical/Cavernous/Grasslands)
  
• 3-3-2-2-2-2-1-1-1-1-(1-1) (Terran)
  
• 3-3-2-2-2-2-1-1-1-(1-1-1) (Ocean, Arid)
  
• 3-3-2-2-2-2-1-1-(1-1-1-1) (Desert)
  
• 3-3-2-2-2-2-1-(1-1-1-1-1) (Radiated)
  
• 3-3-2-2-2-2-(1-1-1-1-1-1) (Barren)

These mining yields can be increased with three colony structures:

• Neutron Collider [Neutrino Physics, Tier 3] increases the yield of each worker by 1.
  
• Robo-Miners [Cybertechnics, Tier 5] increases the yield of each worker by 1.
  
• Deep Core Mining [Tectonic Engineering, Tier 9] increases the yield of each worker by 2.

Klackon and Meklar workers get a +25% yield. Aliens who have yet been assimilated get a -50% yield. Races on the wrong type of Gravity world get a -50% yield.

* This version applied to EA1 & EA2. I am keeping it here for reference purposes.

Next we will talk about the game mechanics for the various planetary types. Due to word limits, I have to break this up into two different sections. We will start by discussing population size, science slots, and the number and value of farming slots:

A. Population Size
B. Science Slots
C. Farming Slots


A. Population Size

The upper limit for population size is determined by the size of the planet but is modified by the available farming and mining cells (which are determined by biome).

• The maximum size for Small planets is a population of 8 (4 farming slots, 4 mining slots).
  
• The maximum size for Medium planets is a population of 12 (6 farming slots, 6 mining slots).
  
• The maximum size for Large planets is a population of 16 (8 farming slots, 8 mining slots).
  
• The maximum size for Huge planets is a population of 20 (10 farming slots, 10 mining slots).

Gaia planets have all farming and mining slots available so the maximum population for a Large Gaia planet is 16. In contrast, a Large Desert planet will have 4 farming slots available (6 closed) and 6 mining slots available (4 closed) so its maximum population is 10.

There are two technologies that may increase the population size of a planet:

• Biomorphic Fungi [Astro Biology, Tier 6] opens up any closed farming slots, which may increase population size. Since Gaia planets are already have all farming slots open they do not increase in maximum size. Large Terran and Uber planets have 1 closed farming slot, so they increase their maximum size by 1 and the slot yields 2 food. A Large Desert planet will gain 6 new slots each yielding 1 food. And Large Radiated, Toxic, and Volcanic planets will increase their maximum size by 10, but all 10 of the farming slots naturally yield 0 food.
  
  
• Advanced City Planning [Galactic Economics, Tier 9] increases the maximum size of all planets by 5 but does not create or open up any new farming or mining slots.

Here is a list of maximum population sizes:

• Small Gaia, Uber, & Terran: 8 max pop --> 8 max pop with Biomorphic Fungi.
  
• Small Swamp & Arid: 7 --> 8
  
• Small Ocean: 6 --> 7
  
• Small Tundra, Desert, & Barren: 5 --> 7
  
• Small Toxic, Radiated, & Volcanic: 3 --> 7
  
  
• Medium Gaia: 12 --> 12
  
• Medium Uber & Terran: 11 --> 12
  
• Medium Ocean: 10 --> 11
  
• Medium Swamp & Arid: 9 --> 11
  
• Medium Tundra, Desert, & Barren: 8 --> 11
  
• Medium Toxic, Radiated, & Volcanic: 4 --> 10
  
  
• Large Gaia: 16 --> 16
  
• Large Uber & Terran: 15 --> 16
  
• Large Swamp & Arid: 12 --> 15
  
• Large Ocean: 12 --> 14
  
• Large Tundra & Desert: 10 --> 14
  
• Large Barren: 9 --> 14
  
• Large Toxic, Radiated, & Volcanic: 5 --> 13
  
  
• Huge Gaia: 20 --> 20
  
• Huge Uber: 19 --> 20
  
• Huge Terran: 18 --> 19
  
• Huge Swamp & Arid: 15 --> 18
  
• Huge Ocean: 15 --> 17
  
• Huge Tundra & Desert: 12 --> 17
  
• Huge Barren: 11 --> 17
  
• Huge Volcanic: 7 --> 17
  
• Huge Toxic & Radiated: 6 --> 17

B. Science Slots

All planets can have an unlimited number of scientist slots.

The number of slots visually displayed is equal to your current population. So if you have a new colony with population 1, only a single scientist slot is shown. But when you increase in population, new scientists slots will be added automatically.

The default yield for each scientist is 1 research. This can be increased with two colony structures:

• Advanced Data Center [Private Funding, Tier 3] increases the yield of each scientist by 1.
  
• Astro University [Teaching Methods, Tier 6] increases the yield of each scientist by 3.

Psilon scientists get a +50% yield. Aliens who have yet been assimilated get a -50% yield.


C. Farming Slots

The planet size determines the maximum number of potential farming slots but the biome determines how many of those are immediately farmable. (Biomorphic Fungi [Astro Biology, Tier 6] eventually opens up the rest).

In addition, both planet size and biome determine the base values of each farming slot.

Here is a listing of farming values for the various planet sizes and types (X means closed off until Biomorphic Fungi):

• Small Gaia & Uber
  4-4-3-3
  
  
• Small Terran
  4-3-3-2
  
  
• Small Ocean (X = 2 with Biomorphic Fungi)
  4-3-3-X
  
  
• Small Swamp (X = 2)
  3-3-2-X
  
  
• Small Arid (X = 1)
  3-2-2-X
  
  
• Small Tundra (X = 1)
  2-2-X-X
  
  
• Small Desert & Barren (X = 1)
  2-1-X-X
  
  
• Small Toxic, Radiated, & Volcanic (X = 0)
  X-X-X-X
  
  
  
• Medium Gaia
  5-4-4-3-3-2
  
  
• Medium Uber (X = 2)
  5-4-4-3-3-X
  
  
• Medium Terran (X = 2)
  4-4-3-3-2-X
  
  
• Medium Ocean (X = 2)
  4-3-3-3-2-X
  
  
• Medium Swamp (X = 2, Y=1)
  4-3-2-2-X-Y
  
  
• Medium Arid (X = 1)
  3-2-2-2-X-X
  
  
• Medium Tundra (X = 1)
  3-2-1-X-X-X
  
  
• Medium Desert & Barren (X = 1)
  2-1-1-X-X-X
  
  
• Medium Toxic, Radiated, & Volcanic (X = 0)
  X-X-X-X-X-X
  
  
  
• Large Gaia
  5-4-4-4-3-3-3-2
  
  
• Large Uber (X = 2)
  5-4-4-4-3-3-3-X
  
  
• Large Terran (X = 2)
  5-4-3-3-3-2-2-X
  
  
• Large Ocean (X = 2)
  5-4-3-3-2-2-X-X
  
  
• Large Swamp (X = 2, Y = 1)
  4-3-3-2-2-X-X-Y
  
  
• Large Arid (X = 1)
  4-3-2-2-1-X-X-X
  
  
• Large Tundra (X = 1)
  3-2-2-1-X-X-X-X
  
  
• Large Desert (X = 1)
  2-1-1-1-X-X-X-X
  
  
• Large Barren (X = 1)
  2-1-1-X-X-X-X-X
  
  
• Large Toxic, Radiated, & Volcanic (X = 0)
  X-X-X-X-X-X-X-X
  
  
  
• Huge Gaia
  5-5-4-4-4-3-3-3-2-2
  
  
• Huge Tropical (X = 2)
  5-5-4-4-4-3-3-3-2-X
  
  
• Huge Terran (X = 2)
  5-4-4-3-3-3-2-2-2-X
  
  
• Huge Ocean (X = ?)
  5-4-4-3-3-2-2-2-X-X
  
  
• Huge Swamp (X = 1)
  4-4-3-3-2-2-2-X-X-X
  
  
• Huge Arid (X = 1)
  4-3-2-2-2-1-1-X-X-X
  
  
• Huge Tundra (X = 1)
  3-2-2-1-1-X-X-X-X-X
  
  
• Huge Desert (X = 1)
  2-2-1-1-1-X-X-X-X-X
  
  
• Huge Barren (X = 1)
  2-2-1-1-X-X-X-X-X-X
  
  
• Huge Toxic, Radiated, & Volcanic (X = 0)
  X-X-X-X-X-X-X-X-X-X

These farming yields can be increased with two colony structures:

• Soil Enrichment Facility [Xenobiotics, Tier 3] increases the yield of each farmer by 1.
  
• Subterranean Farms [Planetology, Tier 5] increases the yield of each farmer by 1.

Klackon farmers get a +50% yield. Aliens who have yet been assimilated get a -50% yield. Races on the wrong type of Gravity world get a -50% yield.

* This version applied to EA1 & EA2. I am keeping it here for reference purposes.

This is the second part of the game mechanics where we discuss the number and value of mining slots, as well as pollution and some game calculations:

D. Mining Slots
E. Pollution
F. Game Calculations


D. Mining Slots

The planet size determines the maximum number of potential mining slots.

The planet size and mineral richness determine the exact value of each slot, which is the same for all planets of a given size.

However, the biome determines how many of those slots are actually mineable. There is no way to open up closed slots because there is no mining equivalent to Biomorphic Fungi.

For Small planets, the distributions are:

• 1-1-1-1 (Ultra Poor)
  
• 2-2-1-1 (Poor)
  
• 3-2-2-1 (Abundant)
  
• 3-3-2-2 (Rich)
  
• 4-4-3-3 (Ultra Rich)

For Medium planets, the distributions are:

• 1-1-1-1-1-1 (Ultra Poor)
  
• 2-2-1-1-1-1 (Poor)
  
• 3-2-2-2-1-1 (Abundant)
  
• 4-3-3-2-2-1 (Rich)
  
• 5-4-4-3-3-2 (Ultra Rich)

For Large planets, the distributions are:

• 1-1-1-1-1-1-1-1 (Ultra Poor)
  
• 3-2-1-1-1-1-1-1 (Poor)
  
• 4-3-2-2-1-1-1-1 (Abundant)
  
• 4-3-3-3-2-2-2-1 (Rich)
  
• 5-4-4-4-3-3-3-2 (Ultra Rich)

For Huge planets, the distributions are:

• 1-1-1-1-1-1-1-1-1-1 (Ultra Poor)
  
• 3-2-1-1-1-1-1-1-1-1 (Poor)
  
• 4-3-2-2-2-1-1-1-1-1 (Abundant)
  
• 5-4-3-3-2-2-2-2-?-? (Rich)
  
• 5-5-4-4-4-3-3-3-2-2 (Ultra Rich)

So for Small Abundant planets you would have the following for different biomes:

• 3-2-2-1 (Gaia, Uber, Terran, Swamp, & Arid)
  
• 3-2-2-X (Ocean, Tundra, Desert, Barren, Toxic, Radiated, & Volcanic)

So for Medium Abundant planets you would have the following for different biomes:

• 3-2-2-2-1-1 (Gaia, Uber, Terran)
  
• 3-2-2-2-1-X (Swamp, Arid, Ocean, Tundra, Desert, & Barren)
  
• 3-2-2-2-X-X (Toxic, Radiated, & Volcanic)

So for Large Abundant planets you would have the following for different biomes:

• 4-3-2-2-1-1-1-1 (Gaia, Uber, & Terran)
  
• 4-3-2-2-1-1-1-X (Swamp & Arid)
  
• 4-3-2-2-1-1-X-X (Ocean, Tundra, Desert, & Barren)
  
• 4-3-2-2-1-X-X-X (Toxic, Radiated, & Volcanic)

So for Huge Abundant planets you would have the following for different biomes:

• 4-3-2-2-2-1-1-1-1-1 (Gaia & Uber)
  
• 4-3-2-2-2-1-1-1-1-X (Terran)
  
• 4-3-2-2-2-1-1-1-X-X (Swamp & Arid)
  
• 4-3-2-2-2-1-1-X-X-X (Ocean, Tundra, Desert, Barren, & Volcanic)
  
• 4-3-2-2-2-1-X-X-X-X (Toxic & Radiated)

These mining yields can be increased with three colony structures:

• Neutron Collider [Neutrino Physics, Tier 3] increases the yield of each worker by 1.
  
• Robo-Miners [Cybertechnics, Tier 5] increases the yield of each worker by 1.
  
• Deep Core Mining [Tectonic Engineering, Tier 9] increases the yield of each worker by 2.

Klackon and Meklar workers get a +25% yield. Aliens who have yet been assimilated get a -50% yield. Races on the wrong type of Gravity world get a -50% yield.


E. Pollution

Each biome also has a natural tolerance for pollution which translates to an inherent –X% a turn (the amount also varies based on planet size). Radiated, Toxic, Volcanic, and Uber planets are essentially immune to pollution. They have a sufficiently large –X% that pollution will never accumulate to 100%. The relative sensitivity is:

Uber & Toxic & Radiated & Volcanic (immune) > Desert & Barren > Arid > Swamp & Tundra > Terran > Ocean > Gaia (most sensitive)

If you Terraform or Gaia Transform a planet, the pollution is reset to 0. If you Uber Transform a planet, the pollution is not reset but the Uber planet's pollution toleration is high enough that total pollution should come down to near 0% after a few turns. Pollution will also gradually decrease while in the process of terraforming or transforming.

Additionally, you can actively clean up pollution by choosing that project from the production list.

If you settle a new colony, at 1 production, the planets would have the following natural pollution rates:

• Small Uber, Toxic, Radiated, & Volcanic: -100%
  
• Small Desert & Barren: -8%
  
• Small Arid: -4%
  
• Small Swamp & Tundra: -4%
  
• Small Terran: -4%
  
• Small Ocean: -3%
  
• Small Gaia: -2%
  
  
• Medium Uber, Toxic, Radiated, & Volcanic: -66%
  
• Medium Desert & Barren: -5%
  
• Medium Arid: -3%
  
• Medium Swamp & Tundra: -3%
  
• Medium Terran: -2%
  
• Medium Ocean: -2%
  
  
• Large Uber, Toxic, Radiated, & Volcanic: -40%
  
• Large Desert & Barren: -3%
  
• Large Arid: -2%
  
• Large Swamp & Tundra: -2%
  
• Large Terran: -1%
  
• Large Ocean: -1%
  
• Large Gaia: -1%
  
  
• Huge Uber, Toxic, Radiated, & Volcanic: -25%
  
• Huge Desert & Barren: -2%
  
• Huge Arid: -1%
  
• Huge Swamp & Tundra: -1%
  
• Huge Terran: -1%
  
• Huge Ocean: -1%
  
• Huge Gaia: -1%

F. Game Calculations

If you look at the Master of Orion wiki, its Biome section gives a few game stats:

• "Base Food per Cell" translates to the value of each farming slot.
  
  
• "Farmable Cells" and "Productive Cells" translates to the number of available slots. The equation seems to be (% of cells) * (maximum number of cells for that planet size), then round up to the nearest integer. This seems to work out for the majority of calculations. The outliers I have noticed are Huge Uber and Terran planets, with 80% farmable cells should yield 8 cells but they actually have 9. And Huge Volcanic planets, with 60% productive cells should yield 6 cells but they have 7. It could be that the actual game numbers are 81% and 61% respectively.
  
  
• "Pollution absorption" gives the relative values of pollution tolerance. Although the wiki says that Swamp & Tundra have the same value and Desert & Barren have the same value, I have seen some slight variation.