I was wondering why I found this story so familiar. It's literally Space Merc Isekai's author doing it from a different angle. Seems to be within the same universe of Stella Online.
Same universe as Space Mercenary, different section of space by a long shot.
This won't spoil anything, but the world building is as such:
There are "upper" and "lower" parallel universes. One day, a space kingdom from a lower universe basically broke reality and nearly ended all universes, but with help from the equivalent of eldritch gods/creatures, they fixed the universe... mostly.
There are weak spots still, and those weak spots are what cause bleed through between universes, causing isekai things to happen.
Or, I suspect, game devs in various other universes to glimpse part of a sci-fi universe and build various games around it. That game then probably becomes something like a gateway that sometimes gives players the full experience. I think.