when I start the game, it seems pretty much every texture/model that doesnt belong to the UI is missing. When selecting character or editing them, they dont show up. The biggest problem however is the fight itself:

https://imgur.com/a/F3QOZad

Is there a solution for that?

Have you tried to change the settings a bit.

There mat be a setting your graphics card do not like.

There are other, more advanced ways to try as well, if you want.

Please list your GPU spec if you want that.

The UI shows, but not the 3d parts. that usually points to something not liking the unity 3d rendering. As the UI on top is in 2d, that works (at least that it how it seems to be).

Options - Graphics - Simple Graphics On

hm, well it does work. But its rather weird, that a AMD Radeon RX 5700 XT isnt able to play on high graphic. Its also the only unity game where i have problems with it. 

How well it runs may be dependent on which unity version the game was made with.

It's not always the case that the developer uses the latest version (do to familiarity, i think).

This isnt a Unity game, not sure what engine it uses, but I dont think its Godot either. There's a few Open Source 3D engines out there, and from looking at all the Open Source DLL's linked, its probably one of them

Try https://enlit3d.itch.io/heroine-rumble-2/devlog/561960/v0103-amd-cards-fix