Hi,
I installed this game via Heroic Games Launcher: Got Linux Mint 20.3 and Nvidia 970 Gtx.

Game Log:

Running BEAUTIFUL DESOLATION

Set current directory to /home/christian/Games/Heroic/BEAUTIFUL DESOLATION/game

Found path: /home/christian/Games/Heroic/BEAUTIFUL DESOLATION/game/desolation.x86_64

Mono path[0] = '/home/christian/Games/Heroic/BEAUTIFUL DESOLATION/game/desolation_Data/Managed'

Mono path[1] = '/home/christian/Games/Heroic/BEAUTIFUL DESOLATION/game/desolation_Data/Mono'

Mono config path = '/home/christian/Games/Heroic/BEAUTIFUL DESOLATION/game/desolation_Data/Mono/etc'

Preloaded 'ScreenSelector.so'

Preloaded 'libsteam_api.so'

Player data archive not found at `/home/christian/Games/Heroic/BEAUTIFUL DESOLATION/game/desolation_Data/data.unity3d`, using local filesystem

Launch command: ['/home/christian/Games/Heroic/BEAUTIFUL DESOLATION/start.sh']

Hi, yes i do think this is the error too.... :-)

But what can I do to fix this error?

This is not the error. That simply says that there is no packed data in a file called "data.unity3d", and it uses the unpacked files in "desolation_Data" instead. This is misleading and happens in case of problems with OpenGL preventing the launch of the game. This happens here when I try to force the use of vulkan, as well as when trying to start something requiring a higer OpenGL version than my graphics chip can handle.

Well, as I said, it is misleading: the file isn't there, was never there, and is not required to run the game.

As I understand it, you can either have the game data packed in this file, or leave it unpacked in subdirectories in the file system. The Unity engine allows both. This game is not „packed“, so it is normal that the file isn't there.

What I've observed is:
IF the game data is unpacked AND IF there is a problem with OpenGL on your machine, you'll get to read this error message.
In fact, you'll get the message also if everything is fine with OpenGL, xou normally just won't notice it.

To pack the data would not help, however.

To make it clear: all the messages in the posted log are normal.
If the game doesn't start, the problen is something else!