Anvilium

You are not the monster. You are what is wearing it.
Something came through a tear between dimensions and arrived with no body of its own. It has one now. Whichever creature on this planet happens to be the strongest, that is what it wears, and it keeps trading up.
Defeat it, read it, grow it
Every creature you meet is carrying something worth taking. Defeat one and its exact loadout gets written into that species' archive, ability by ability, mutation by mutation. Collect enough of a species and you can sequence its genome outright, which unlocks it for synthesis.
Every unit you synthesise is a fresh roll. Its own stats, its own spread, built from whatever you have encoded. Two of the same species are never the same animal, and chasing the perfect one is most of the game.
300+ creatures across eight tiers of power, from scavengers to apex horrors

150 Abilities and 150 Mutations, four slots each, which works out to roughly 410 trillion loadouts on a single unit before you touch its gear

A Genome Codex that remembers every species, ability and mutation you have ever seen

Genes spliced into six slots per creature. Not gear you equip, biology you rewrite.

An army that thinks for itself
You do not give orders. You write instructions.
Every unit runs a list of Instincts, priority rules you set before the fight starts. Protect whoever is hurt. Focus anything attacking me. Burn what is already frozen. Once the battle begins your creatures read the field and act on those rules, without waiting on you.
Which frees you up for the one thing a parasite is actually for. Possess your best creature and fight inside it.
The roll goes all the way down
Two creatures of the same species are never the same animal, and it is not only their stats that differ. The points invested in each Ability and Mutation are rolled as well, so one Hell Hound's Fireball leans on raw damage while another throws more projectiles. Level a creature and you earn points to push those numbers wherever you want them. What you start with is what you were given.
Two ways onto a planet
Exploration puts you alone in your host among creatures that will ignore you until you touch them. This is where you meet new species and take what you need from them.

War sends your whole army against a planet that is hunting back. Nothing here is passive and nothing here is your level by accident.

Every planet is a seed
Worlds generate whole from a single seed. The species living there, their tiers, the abilities they carry, the rolls on their stats. Copy the seed and another player lands on the same planet you did, down to the mutation on the third creature they meet. Find something rare and it is worth telling people about.
Also in the box
Hand-built biomes, each with its own species pool and its own hazards

Formations you draw yourself, saved and swapped between fights

A parasite that levels alongside the army. Your power is you, not the body you happen to be wearing.