So yeah, I'm trying to find a very specific mecha anime or manga.
Now I might be remembering wrong but I'm pretty sure I read it, though at the same time I'm not sure.
What I remember is that the MC who is some random bloke that spent alot of time at the arcades playing some kind of mechasimulator-game suddenly get into some training program, either by magically transporting to a different dimension or whatever it was. He gets there and sits in the "official" battle-simulators and aces everything.

For the part which I am uncertain if it's Knights of Sidonia (watching the anime atm) or the same series:
He starts helping the development team with improving their mecha suits by running simulations and actual combat and so on.
I've read the knights of sidonia manga before watching the anime, this might be why I'm mixing the two series but I'm basically unsure.
TYVM for your help!

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Idk how many different mangas, manhuas or manhwas that I've read but it's more than 3000. More to come!
(Number of H-mangas and one-shots: unknown and not included)

Over 180 anime shows watched and there's a vast sea of shows to go.

J/K-drama's 50+ shows watched.
It's Mr to you!

Might be Super Robot Taisen: Original Generation - Divine Wars

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~4400 manga completed
~1700 ongoing...

Sounds very similar to what I imagined. I'll try to find it somehow so I can watch it. I might have streamed it thought and I couldn't find it on my go-to streamers page.

________________
Idk how many different mangas, manhuas or manhwas that I've read but it's more than 3000. More to come!
(Number of H-mangas and one-shots: unknown and not included)

Over 180 anime shows watched and there's a vast sea of shows to go.

J/K-drama's 50+ shows watched.
It's Mr to you!