The only really Specific thoughts I have for this universe are for Earth + a handful of species :^)

Gonna update w/ more on the alien species once I get a chance to dive into it, but I've had Earth figured out from another story for awhile now so I thought I'd finally put it all somewhere :o

Earth (100 mil years from present)

Large asteroids crashed, leaking radiation and later hatching colossal aliens later named Finitus. Despite desperate battle efforts for hundreds of years, the Finitus spread, leaving destruction and mutated creatures in their wake.

All humans have a physical radiation-fueled mutation of some kind. Severity and type can vary widely. Some simply have large patches of scaly/thick skin or an oddly proportioned body part, but some have multiple limbs/eyes, missing parts, exposed bones, and some special abilities such as expelling acidic blood/enhanced strength (real Resident Evil hours) The more severe ones can present as minor at first, until stress or emotional trigger activates it. 

In present timeline, the moon has long since been terraformed and it, along with 2 more man-made moons, host over half of the human population. The other half have evolved separately, adapting to their new harsh environment.

Inhabitants

Earthlings

- Many still on earth are just simply folks who could never afford to live on the Moons, and live relatively normal lives. They're low-tech and are generally suspicious of all aliens, as the horror stories of the invasion have been told in increasing grandeur throughout the ages.

- It's not uncommon for one to re-purpose ancient war refuse as enhancements to compensate for their mutations (or simply to replace limbs lost to predators/unusable due to mutation). The tech they work with is very modest, often plain and practical in design, and shows signs of rusting or cracking. Clothing is rough-looking from wear. Can range widely from cloaks to wool shirts, but always with practicality and climate in mind. Whole animal pelts are widely used for warmth/armor while on long hunts, and bandits will sometimes wear the skulls to boast their toughest kills.

- Animals/plants were affected by radiation as well, and have gotten much bigger in size while displaying similar mutations as humans. Earthlings face more of a threat from wild animals & each other then they do Finitus nowadays.

- The largest cities and communities are often built around/in old warships and weaponry for protection, as Finitus will avoid going near them when active. Most live relatively normal lives as farmers/craftsman/scavengers, and are content with their place in the world. Others live as outlaws or bandits, and war amongst themselves for resources/territory.

- It's uncommon to see earthlings very far off-planet, as most don't make enough to afford to travel or simply have no interest.

Lunalings

- Highly advanced technologically, as after they joined the Collective they've had a better trade/social relationship over the ages with other aliens. Scientists, scholars, and dignitaries make up most of the First Moons people, and the other two are civilian populated. 

- They mostly ignore Earth/Earthlings outside of doing trade. They consider the old war a stain and a failure of the human race, and the mutations suffered by humans a hopeless tragedy. They believe science and robotics are the way to reach humanities highest potential.

- They have MUCH tamer mutations due to spending hundreds of years away from earth, and most have the resources to replace or heal theirs as soon as possible in life. Lunalings may even go so far as to transfer their organs to an android body at some point, as it's considered more efficient and has multiple health benefits.

- Cybernetic limbs and enhancements are common for both fashion and scientific purposes. Tend to be sleek and shiny, with lavish and ornate designs.

- Each moon has it's own atmosphere and environments, and each have a portion dedicated to preserving old Earth knowledge.

AFTER VERY SPECIFIC EARTH STUFF It really opens up nd just,,, Aliens In General are around space so Go Nuts

Here's the ones that i already got Somewhat Established but no concrete lore yet outside of rough stuff hhhh 

These are just my datesim aliens for now btw, 1) bc I'm already working on these heckers rn and 2) bc I'm afraid I'll get burnt out if I try balancing too many right away (also none of the species have names yet YEET)

Birdos 

- Tall bird based humanoids. 

- The most well-traveled of all alien species, and the leaders of a Collective of Planets vowed to peace and prosperity shared between them. It's the most widespread known force of peace and technological advancement in the galaxy, and most civilizations that have figured out space travel know of it.

Similar to star trek's federation, but with a more intimidating and ominous presence despite their peaceful message. Many join when approached simply out of fear of whatever the alternative may be.

- Multiple sets of wings, long limbs, and 6 eyes are the main staples, alongside a variety of psychedelic plumage colors + patterns

- Native language is Cosmic, an abstract language spoken in shape and color. Oddly similar to Squidward's language, despite little to no contact between the two. Impossible for most other beings to understand, and can cause a horrendous stress response often leading to fainting or even death if listened to for too long. 

Bc of that they usually whisper to each other, or just speak the language of whoever they're around (of which they have a unique ability to pick up extremely quickly)

Ratboy Genius 

- Centaur Aliens with rodent-like bottom half and big-cat/humanoid top half

- Very Klingon-esque, but less pigheaded. They value and respect you based on your ability to defend yourself and your loved ones. Has many natural enemies on home planet, which is why some chose to join Birdos as an elite military force for the Collective in exchange for safety.

- Colorful horns, and colorful organic glowing strands growing out their back. they have natural patterns + fur colors that correspond w/ rodents & big-cats, and vibrant colors for horns/back strands 

Squidward 

- Cthulu-like aliens that originated on earth, and evolved quickly due to the radiation. 

- Very colorful like their octopus cousins, tentacles placed like horns on head, plated teeth, platypus-like hands and tentacle tails.

Bugs Life 

- Insect humanoids

- Live in vast Monarchies resembling hive structure, but w/ hive mind being something individuals can slip in and out of. Usually have very strong flying militaries, and put a focus on loyalty to country and to the Monarch.

- May be based on any winged insect, have 2 sets of arms and wings.

Spacedust 

- Sapient clouds of cosmic energy, can take multiple forms and freely fly through space without worry. 

- Families are very close and travel merged together in giant luminous clouds, If broken up or destroyed, the lone spacedust will seek close bonds with other lifeforms. 

- No specific visual indicators, aside from being made of space-stuff + faces being very basic eyes & mouth

Void 

- Black tar that can posses and puppet a host (host can be alive, dead, or inanimate, but decommissioned robots are a popular vessel for some reason)

- A mysterious entity, they don't share their history or secrets as readily as others. 

- Once solidified in a host, the tar takes a more solid tree-root look and eyes sprout from it.