TerraGenesis Wiki
TerraGenesis Wiki

Map of Lethe and it's colonies

Lethe was one of humanity's first successful colonies in another solar system. It was thriving, a jewel of our burgeoning galactic civilization, until ten years ago when the entire population, almost 50 million people, vanished.

You have been tasked with investigating the mass disappearance, and your ship is about to make landfall. Begin by establishing Habs in the abandoned colonies to get them up and running. From there you can begin to re-populate the planet, and try to figure out what happened.


Lethe Is a fictional planet in TerraGenesis, and one of the two planets that already has cities when you start, the other being Earth. Lethe's cities are abandoned, so build habitations first.

If you play Lethe with the Biospheres function, it starts out with a lot of the same species as Earth does. Additionally, the starting biosphere is not oxygen neutral. The planet gains 15 parts per million of oxygen per minute. You will need to counteract this quickly. If you let the planet go, all species will die out.

Lethe has one moon, Moneta of size class III (average).


Lethe already has empty cities, so you don't need to spend space credits on buying those, which you can use to your advantage. Place basic hab units (that don't change anything about temperature, pressure, water or oxygen levels) and wait for the The League random event to pop up a couple of times, so you get ridiculous amounts of revenue. You can save terraforming for after you get all that revenue.

Assuming you play with Biomass, you can basically turn off any terraforming buildings Lethe has in order to save credits, and it will be okay, because Lethe is already habitable anyways. Since the planet is already habitable, all you need is spaceports to increase population, and native birthrate will take care of the rest. The planet's massive amount of starting biomass is enough to support hundreds of thousands of people for a number of days - enough time to get started with coral reefs and spaceports, even Sequestration Plants.

If you play with Biomass the only thing you need to counterbalance is the spaceports. If you play with Biospheres you'll also need to balance out your oxygen levels, either with oxygen filters, or with preexisting higher level facilities. However, the latter may not always be possible.

Temperature, oxygen and water are already at paradise levels, making a gaian playthrough only require pressure reduction and, if not using biospheres mode, an increase in biomass. If in biospheres mode, plant support is already sufficient.


Lethe has 78 species when you first start a new world. Click the links for more info on biospheres and phyla and traits. It's the exact same biosphere Earth has.

Species Phylum Trait 1 Trait 2 Trait 3 Kingdom DNA
Psychrophiles Archaea Cold Adapted Cold Adapted Cold Adapted Aquatic Microorganisms AAAATGGATGATGAT
Thermophiles Archaea Heat Adapted Heat Adapted Heat Adapted Aquatic Microorganisms AAAATGGAAGAAGAA
Anabaena Cyanobacteria Nitrogen-Fixing Nitrogen-Fixing Nitrogen-Fixing Aquatic Microorganisms AAAATCCTTCTTCTT
Lyngbya Cyanobacteria Large Infectious Infectious Aquatic Microorganisms AAAATCGGACTACTA
Oscillatoria Cyanobacteria Large Large Beautiful Aquatic Microorganisms AAAATCGGAGGAGCG
Stromatolite Cyanobacteria Large Low Oxygen Adapted Large Aquatic Microorganisms AAAATCGGAGTTGGA
Coscinodiscophyceae Diatom Low Metabolism Low Metabolism Low Metabolism Aquatic Microorganisms AAAAGAGGCGGCGGC
Large Diatom Diatom Large Large High Metabolism Aquatic Microorganisms AAAAGAGGAGGAGGG
Pennales Diatom High Metabolism High Metabolism High Metabolism Aquatic Microorganisms AAAAGAGGGGGGGGG
Large Plankton Plankton High Metabolism Large Large Aquatic Microorganisms AAAAGTGGGGGAGGA
Phytoplankton Plankton High Metabolism Photosynthetic Photosynthetic Aquatic Microorganisms AAAAGTGGGCGGCGG
Zooplankton Plankton High Metabolism Large High Metabolism Aquatic Microorganisms AAAAGTGGGGGAGGG
Stonewort Stonewort Small Cold Adapted Humidity Adapted Aquatic Algae AATAGGGGTGATGTG
Chlorella Green Algae Photosynthetic Photosynthetic Small Aquatic Algae AATAGCCGGCGGGGT
Green Algae Green Algae Small High Metabolism High Metabolism Aquatic Algae AATAGCGGTGGGCGG
Killer Algae Green Algae Small Invasive Invasive Aquatic Algae AATAGCGGTCAACAA
Marimo Green Algae Cold Adapted Beautiful Delicate Aquatic Algae AATAGCGATGCGCAG
Watermelon Snow Green Algae Beautiful Cold Adapted Cold Adapted Aquatic Algae AATAGCGCGGATGAT
Giant Kelp Kelp Large Large Large Aquatic Algae AATACAGGAGGAGGA
Macrocystis Kelp High Metabolism High Metabolism High Metabolism Aquatic Algae AATACAGGGGGGGGG
Sargassum Kelp High Metabolism Large Heat Adapted Aquatic Algae AATACAGGGGGAGAA
Seaweed Seaweed High Metabolism Invasive Domesticated Aquatic Algae AATACTGGGCAAGCT
Wakame Seaweed Cold Adapted Invasive Fruit-Bearing Aquatic Algae AATACTGATCAACGA
Soft Coral Coral Beautiful Delicate Delicate Aquatic Herbivore AAGACGGCGCAGCAG
Stony Coral Coral Beautiful Beautiful Delicate Aquatic Herbivore AAGACGGCGGCGCAG
Shrimp Crustacean Small Domesticated Domesticated Aquatic Herbivore AAGACCGGTGCTGCT
Parrotfish Fish Large Beautiful Beautiful Aquatic Herbivore AAGTAAGGAGCGGCG
Reef Fish Fish Small Beautiful Heat Adapted Aquatic Herbivore AAGTAAGGTGCGGAA
Manatee Mammal Large Low Metabolism Large Aquatic Herbivore AAGTATGGAGGCGGA
Whale Mammal Large Large Large Aquatic Herbivore AAGTATGGAGGAGGA
Sea Turtle Reptile Large Low Metabolism Beautiful Aquatic Herbivore AAGTAGGGAGGCGCG
Spider Crab Crustacean Large Large Scavenger Aquatic Carnivore AAGACCGGAGGACCC
Salmon Fish Social Behavior Large Domesticated Aquatic Carnivore AAGTAACCAGGAGCT
Tuna Fish Large Large Domesticated Aquatic Carnivore AAGTAAGGAGGAGCT
Seal Mammal Cold Adapted Cold Adapted Social Behavior Aquatic Carnivore AAGTATGATGATCCA
Shark Mammal Large Social Behavior High Metabolism Aquatic Carnivore AAGTAAGGACCAGGG
Crocodile Reptile Heat Adapted Heat Adapted Large Aquatic Carnivore AAGTAGGAAGAAGAA
Frankia Actinobacteria Nitrogen-Fixing Nitrogen-Fixing Nitrogen-Fixing Terrestrial Microorganism AACATGCTTCTTCTT
Nocardia Actinobacteria Large Infectious Airborne Terrestrial Microorganism AACATGGGACTACTG
Soil Bacteria Actinobacteria Large Nitrogen-Fixing Nitrogen-Fixing Terrestrial Microorganism AACATGGGACTTCTT
Streptomyces Actinobacteria Nitrogen-Fixing Airborne Infectious Terrestrial Microorganism AACATGCTTCTGCTA
Arctic Lichen Lichen Cold Adapted Cold Adapted Small Terrestrial Microorganism AACTTAGATGATGGT
Crustose Lichen Large Beautiful Beautiful Terrestrial Microorganism AACTTAGGAGCGGCG
Tree Lichen Lichen Cold Adapted Low Metabolism Beautiful Terrestrial Microorganism AACTTAGATGGCGCG
Black Mold Fungus Poisonous Poisonous Invasive Terrestrial Microorganism AACTTTGCCGCCCAA
Bracket Fungus Fungus Large Nitrogen-Fixing Beautiful Terrestrial Microorganism AACTTTGGACTTGCG
Honey Mushroom Fungus Large Large Large Terrestrial Microorganism AACTTTGGAGGAGGA
Yeast Fungus High Metabolism Domesticated Domesticated Terrestrial Microorganism AACTTTGGGGCTGCT
Malaria Protozoa Poisonous Infectious Poisonous Terrestrial Microorganism AACTTGGCCCTAGCC
Bamboo Grass Large Large High Metabolism Terrestrial Plant ATATTCGGAGGAGGG
Cereal Grains Grass Domesticated Cash Crop Fruit-Bearing Terrestrial Plant ATATTCGCTCTCCGA
Lawn Grass Grass Small Domesticated Domesticated Terrestrial Plant ATATTCGGTGCTGCT
Tussock Grass Cold Adapted Large Large Terrestrial Plant ATATTCGATGGAGGA
Sheet Moss Moss High Metabolism Small Domesticated Terrestrial Plant ATATGAGGGGGTGCT
Tree Moss Moss Humidity Adapted Cold Adapted Beautiful Terrestrial Plant ATATGAGTGGATGCG
Flowerbush Shrub Flowering Beautiful Cash Crop Terrestrial Plant ATATGTCGCGCGCTC
Hedge Shrub Large Domesticated Cash Crop Terrestrial Plant ATATGTGGAGCTCTC
Ivy Shrub Domesticated Invasive Flowering Terrestrial Plant ATATGTGCTCAACGC
Maple Tree Deciduous Large Beautiful Terrestrial Plant ATATGGCGTGGAGCG
Palm Tree Heat Adapted Humidity Adapted Fruit-Bearing Terrestrial Plant ATATGGGAAGTGCGA
Pine Tree Cold Adapted Cold Adapted Cash Crop Terrestrial Plant ATATGGGATGATCTC
Redwood Tree Large Large Large Terrestrial Plant ATATGGGGAGGAGGA
Parrot Bird Beautiful Beautiful Beautiful Terrestrial Herbivore ATTTCAGCGGCGGCG
Ant Insect Small Social Behavior Social Behavior Terrestrial Herbivore ATTTCTGGTCCACCA
Bee Insect Small Flying Social Behavior Terrestrial Herbivore ATTTCTGGTCCTCCA
Beaver Mammal Humidity Adapted Humidity Adapted Pair Bonding Terrestrial Herbivore ATTTCGGTGGTGCCG
Camel Mammal Heat Adapted Aridity Adapted Aridity Adapted Terrestrial Herbivore ATTTCGGAAGTCGTC
Deer Mammal Cold Adapted Social Behavior Beautiful Terrestrial Herbivore ATTTCGGATCCAGCG
Elephant Mammal Large Large Large Terrestrial Herbivore ATTTCGGGAGGAGGA
Horse Mammal Large Domesticated Beautiful Terrestrial Herbivore ATTTCGGGAGCTGCG
Iguana Reptile Heat Adapted Low Metabolism Humidity Adapted Terrestrial Herbivore ATTTCCGAAGGCGTG
Tree Frog Amphibian Small Beautiful Poisonous Terrestrial Carnivore ATTTGCGGTGCGGCC
Bird of Prey Bird Large Flying Beautiful Terrestrial Carnivore ATTTCAGGACCTGCG
Beetle Insect Small Beautiful Invasive Terrestrial Carnivore ATTTCTGGTGCGCAA
Bear Mammal Cold Adapted Cold Adapted Large Terrestrial Carnivore ATTTCGGATGATGGA
Big Cat Mammal Heat Adapted Large Social Behavior Terrestrial Carnivore ATTTCGGAAGGACCA
Wolf Mammal Cold Adapted Social Behavior Nocturnal Terrestrial Carnivore ATTTCGGATCCACAT
Snake Reptile Small Beautiful Poisonous Terrestrial Carnivore ATTTCCGGTGCGGCC


  • Lethe is named after the Greek God Lethe who was a spirit of forgetfulness and oblivion.
  • When you start on Lethe, it's surface is red and dusty. In the Ending Cutscene, it is stating that it’s pinkish-redish sand is natural to Lethe.
  • In Roman mythology, Moneta (Latin Monēta) was a title given to two separate goddesses: the goddess of memory (identified with the Greek goddess Mnemosyne) and an epithet of Juno, called Juno Moneta (Latin Iūno Monēta). 

Victory - Spoiler Alert![]

The mass disappearance on the planet is caused by a disease called the Lethe Plague. The Lethe Plague attacks the brain and causes a complete loss of memory. The disease event will slowly decimate the planet's landing party and any population it has established.

Unlike other planets, the objective on Lethe is to find a cure for the disease before the population reaches 0. However, it still uses the concept of using Culture Points to achieve victory; a cure for the Lethe Plague would be found when the victory bar reaches 100%.

On my playthrough of Lethe I was able to finish before the Plague ever made an appearance. I assume this was because I saved up 20 culture points and spent them all at once. This would need confirmation by multiple players, but it seems likely that the Plague only gets introduced after you reach a certain victory (or in Lethe's case it's called investigation) score.

Victory Text[]

Terrestrial Planets Mercury · Venus · Earth · Moon (Luna) · Mars
Moons of Gas Giants Moons of JupiterMoons of SaturnMoons of UranusMoons of Neptune
Moons of Jupiter Io · Europa · Ganymede · Callisto
Moons of Saturn Tethys · Dione · Rhea · Titan · Iapetus
Moons of Uranus Miranda · Ariel · Umbriel · Titania · Oberon
Moons of Neptune Triton
Dwarf Planets Ceres · Pluto · Charon · Makemake · Eris · Sedna
TRAPPIST-1 Damu · Aja · Huanca · Ruaumoko · Asintmah · Ostara · Aranyani
Fictional Planets Bacchus · Pontus · Lethe · Ragnarok · Boreas
Historical Earths Vaalbara · Rodinia · Cambria · Cretacea · Dania · Chibania · Ultima
Random Planets