The selected language is not saved after the game is restarted.

[zexdrak]

Upon restart the game inherits the Steam interface language.

[kevin.harwood]

Thank you for letting us know! We'll get this patched in!

[zexdrak]

Originally posted by kevin.harwood:

Thank you for letting us know! We'll get this patched in!

OK.
The game does not start now.
"There is no data folder" log error.
Thank you for customer support.

[zexdrak]

Maybe this: https://forum.unity.com/threads/solved-there-is-no-data-folder.364065/

Building a game project on OSX for Linux (standalone with/without headless), and when execute it on Linux does still produce an error (after downsizing harddrive, chmod, install 32 & 64 bit versions, updating bios & drivers, etc, etc):

"There is no data folder"

But, when installing Unity-Editor 5.1 on Linux and build the same project (project original created on OSX), it will run and execute "so so" correctly (encountered an issue with Resources.Load when using "/" in paths ).

Solution: when building for Linux (on other platforms), a "projectname_Data" folder is additionally created, which also have to be moved alone with the standalone

Since I bought the game I haven’t managed to play it...

[zexdrak]

Originally posted by tℨopc:

Probably not. I think if this was the problem then the game wouldn't work for anyone. The game does work for me on Fedora just fine.

You're going to need to find something where it doesn't affect all users as in the release project isn't broken but something on the user side is causing it to break.

I can test the language too and it will probably work after a restart.

I have more than 200 Unity3D games and only 2 of them don't start, both with the same error.

[zexdrak]

I found the cause of this error.
My Steam library folder is on an USB external drive (/mnt/ExtHDD/steam), not in the default Steam path ($HOME/.local/share/Steam). Moving Steam library to the default folder corrects this error, and the game starts. But this is a problem of the game (or Unity3D bug).
But all other Unity3D games (more than 200) work fine. Only your game and another one (Seeds of Resilience — Unity3D version 2017.1.1f1) doesn't start with same error.
Tested on Ubuntu 19.04 (GNOME 3), Manjaro 18.0.4 (Xfce/KDE Plasma), Linux Mint 19.1 (Cinnamon), Ubuntu 16.04.6 (Unity Desktop).

steam != Steam

[zexdrak]

Originally posted by tℨopc:

Originally posted by zexdrak:

I have more than 200 Unity3D games and only 2 of them don't start, both with the same error.

I have more than x number of Unity games and all of them that are Linux native start including this one.

О, сколько нам открытий чудных
Готовят просвещенья дух
И опыт - сын ошибок трудных,
И гений - парадоксов друг,
И случай - бог-изобретатель...

А. С. Пушкин, октябрь — ноябрь, 1829

How many blissful revelations
The spirit of enlightment hides!
And then experience born of lapses
And genius antinomy-wise
And chance, the heavenly inventor...

A.S. Pushkin, October - November, 1829

[zexdrak]

Originally posted by tℨopc:

There's an amazing amount of combinations possible on Linux. At the very least, some will cause problems even in very specific situations. - Me 2019

Bravo.

Originally posted by tℨopc:

You're going to need to find something where it doesn't affect all users as in the release project isn't broken but something on the user side is causing it to break.

I can test the language too and it will probably work after a restart.

"Something on the user's side" is the option in Steam Settings.
Have you tested the game language and a path with "steam"?

[zexdrak]

Originally posted by tℨopc:

Hope the best for you. But, there's a good chance you will have to look for a solution on your side.

I found the above solution to the problem, but I bought the game for the money and use only standard Steam features. Sellers (developers), not the buyer (a player who bought a game) should solve the problem.