A note on the names: The kids didn't name anything so I've taken the liberty to give temporary names to all races and locations until such time as the young game designers come up with more proper names. If the names sound silly, that's on me.
The planet Reim is located in a binary star system inside the deep core of a distant galaxy. The only way to reach it is through a wormhole that may or may not be bi-directional. Navigation is difficult due to the presence of both a star and a black hole that cause celestial objects to move erratically, and an asteroid field that includes giant space monsters (like any good asteroid field should). An ancient spaceship of unknown origins is hidden inside one of the asteroids. It's possible that the builders of the vessel have also created all life in the system.
Reim's moon is a gas dwarf that can help newcomers refuel after the arduous journey. It has another moon that's mostly covered in lava. There is nothing of interest on it.
The planet of Reim has an elliptical atmosphere that makes some regions of the planet uninhabitable due to high pressure or near total lack of air. The atmosphere shifts on occasion, forcing entire nations to have air shelters in the same way people on earth have bomb shelters. The planet is mostly dry, but has occasional geyser outbursts than can drown (and cook) entire regions.
All creatures on the planet can crossbreed regardless of genetic compatibility. Because of this, the planet has an incredible diversity of sapient species.
Nehashim are the dominant species of the planet. They are a race of winged snakes separated into two hostile superpowers. While both nations appear from the outside to be progressive democracies, both are in fact secretly ruled by sinister aliens (see below). Nahashim randomly evolve into various fantastic shapes as they grow older. (Sort of like Pokemon...)
Pilim are low density animals that are miles tall but squeeze to the size of mice when scared. This helps them survive rapid atmospheric shifts and the occasional boiling geyser.
Atalefim are blind flying mammals that can control gravity, which they use for locomotion, combat and orientation. They also have an aquatic and an underground variety, who appear very different but are in fact closely related.
The Uberton is a hivemind of microorganisms that can steal some (or all) of the brain power of sentient creatures to increase the memory and processing of a biological super computer. It it is the most intelligent being on the planet, but its objectives are unknown and unknowable.
The Western Nehashim nation is secretly ruled by an alien brain implanted in the body of a small cat-like animal possessed of unspeakable telepathic powers. The Eastern nation is ruled by a giant underground monster that can influence people by injecting them with various chemicals through a network of mono-molecular tentacles spread all over the state.
The Atalefim have two states that speak different languages. Both consist of a single word that means everything. Because of this, no universal translator can help foreigners to communicate in either language, nor can one nation learn the language of the other.
There are also three hostile religions which are really just fronts for powerful crime organizations that deal in weapons and drugs that are sold to the faithful in fake religious ceremonies. One of these organizations has strong ties to the government of the Western nation.
There are also several small countries that compete over who will breed the most perfect citizens by use of cosmosium (see below). They are nominal democracies controlled by ruthless scientific and/ or business groups.
- Reim contains a unique chemical known as cosmosium that allows ordinarily incompatible creatures to crossbreed. It is an artificial and alien creation, but it is unknown who has created it and why. Since it's naturally occurring on Reim, many creatures consume it by instinct, not knowing its amazing properties.
- Deep under the surface of the planet there is an ancient workshop that allows anyone to create new forms of life by feeding data into an alien super computer. It's possible that this workshop is the source of all sapient life on the planet.
- The asteroid field is rich in minerals. However, this isn't rare. What is rare is that one of the asteroids is alleged to hide an ancient ship of the same race that has brought the cosmosium and crafted the workshop of life.