Modified Humans – Crout
In most sci fi the aliens all look like slightly modified humans whereas in Traveller they mostly are modified humans – modified by the Ancients to suit a particular planet – which is good really as creating believable and cool alien cultures is hard.
Crout are descended from the Tcho-Tcho variety of modified human seeded by the Ancients to terra form low oxygen planets.
Small planet, very thin, tainted atmosphere – oxygen vs CO2.
Lots of sea life but barren land apart from microbial mats Crout grow for food.
Crout are short, thin with large chests and large eyes and can breath the atmosphere without problem. They have a blue-ish tint and both their eyes and the whites of their eyes are blue.
World is made up of many densely packed small towns, four houses stacked on top of each other, narrow pedestrian streets – Crout like being close together – agriculture and light industry. Each township is self-governing. Culture is dominated by religion officiated over by a matriarch priestess one for each town. (Amish-like) Very strict about violence.
Crout is mostly self-sufficent and has very little to trade.
Small planet, very thin, tainted atmosphere
A Crout heresy led to division and civil war some time in the past and an eventual exodus of the heretics to the very similar planet of Horosho.
The main difference is the heretics have a heirarchical priesthood with a supreme leader.
The Horosho Crout have developed higher tech including ships.
The Horosho Crout sometimes send missionary ships to Crout often sparking trouble.
Some Crout leave home for a few years in their youth to travel. Crout / Crout often work as and make good stewards. Horosho / Crout have a wider variety of skills and are less amiable on average.
Being adapted to a very thin atmosphere Crout need to breath through a filter in a standard atmosphere or they get drunk from the oxygen.
Crout who get addicted to this are called “airheads”.