When an old mistake of the Confederation (namely, a pod holding biological weapons that was sent away after the last war) rears its ugly head on a primitive planet, called Equus by its inhabitants, they call in Praeratus, a former super soldier turned monster hunter, to take care of it before something happens. When nexpected events (namely, a certain megalomaniac king) end up with the thing open and the monsters free, Praeratus is forced to stay on the planet to hunt them down before they slaughter the natives... and force him to take drastic measures to kill them.

While in Equus he will face things known to him, but he'll also rediscover things he didn't know he actually needed: genuine peace and tranquility, new friends... and to be able to love and be loved again.

-Will be mainly a crossover with Stellaris (lasers for armor/bullets for shields, how non-Equus species are described, spaceborne aliens, all that), but will add minor games in the future.
-Humans never existed on Equus (besides the mirror), so when Lyra asks Praeratus about them he will understandably be confused on how the hell does she know about them.
-Profanity used will be both real (damn or s**t) and ficticional (frack or frell) to give it a closer feel to sci-fi instead of just using normal swear words
-Praeratus, the OC, is purposely overpowered because he's a former Spartan/Jedi expy, and his (original, don't have portrait in Stellaris) entire species are basically the Gorn from Star Trek (except they're warm blooded, have the longevity of krogan, and are actually a branch of pelycosaurs, not fully reptiles). However, he'll be only OP in Equestria against Equestrians (various monsters and anypony who pisses him off enough or hurts Cyranus): the monsters and anything from outside Equus (and natives with alien influence) will give him real trouble.
-Equus is not in the Milky Way, rather it's actually part of a dwarf galaxy with a lot more of leviathans where weird stuff happens.
-Some characters, like Celestia, will have fanon-typical traits like large breasts and wide hips, and Praeratus will end up banging Celly in the future, but this is not one of those stories with sex each five chapters; most of the story will be killing, speaking or interacting with natives, and even when we arrive to thesex don't expect it to be good, I'm bad at writing sex.
-For the record, Praeratus is not human, is WAY older than 18-24 (in fact, he's by comparison a bit older than Celestia), and he's not going to just let ponies and othe Equus natives call him things: he'll insult back and outright call them things too (and not just Stellaris insults; in fact, those who think they insult him by calling him dragon might as well be complimenting him).
I don't own MLP: FIM, Stellaris, or the cover art for that matter, but I do own the OC and his species.