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.

About[edit | edit source]

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).

Strategy[edit | edit source]

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.

Trivia[edit | edit source]

  • 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![edit | edit source]

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[edit | edit source]

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
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