Hi there! To confirm, when running the game under Proton you get a background01.vtf crash? That's the error message?

Originally posted by Raptor:

Hi there! To confirm, when running the game under Proton you get a background01.vtf crash? That's the error message?

Yes, that happens under Proton with no other modifications. Everything below first paragraph (which I marked with the line) concerned trying to use native Linux version of HL2 directly.

How are you launching Kreedz Climbing normally? Via steam launch options? If not, what's your command line?

Originally posted by Raptor:

How are you launching Kreedz Climbing normally? Via steam launch options? If not, what's your command line?

For a normal launch I used no launch flags, just the first available launch option (launch game, no borderless) and that's it.

Thanks! Please try verifying the game file integrity if you haven't already!

Originally posted by Raptor:

Thanks! Please try verifying the game file integrity if you haven't already!

Been there, done that, reinstalled from scratch multiple times as well.

Have you managed to play successfully on Proton in the past, or is this your first time playing the game?

Originally posted by Raptor:

Have you managed to play successfully on Proton in the past, or is this your first time playing the game?

Nope, I never played it before. I tried Proton 7.0-4, Experimental, 6.-something and Wine, didn't work in any case.

What was the exact error message you're getting please, to confirm?

Originally posted by Raptor:

What was the exact error message you're getting please, to confirm?

Error!
Can't find background image 'materials/console/background01_widescreen.vtf'

The common error that indicates there's a problem with gameinfo.txt and the mod is not mounted properly.

Thanks! I was suspecting gameinfo.txt too but it doesn't make much sense because things work fine on Windows and this seems to be a Proton only issue...

Please try replacing your gameinfo.txt with this one: https://www.dropbox.com/s/agys3jqe3mobexx/gameinfo.txt?dl=1

I've replaced the paths with direct ones that might bypass any issue with resolving the paths, if that doesn't work we can try something else!

Originally posted by Raptor:

Thanks! I was suspecting gameinfo.txt too but it doesn't make much sense because things work fine on Windows and this seems to be a Proton only issue...

Please try replacing your gameinfo.txt with this one: https://www.dropbox.com/s/agys3jqe3mobexx/gameinfo.txt?dl=1

I've replaced the paths with direct ones that might bypass any issue with resolving the paths, if that doesn't work we can try something else!

Sadly, no difference... Same error, I tried launching both through Proton and using HL2's native executable as per the OP.

Could you confirm that you have a KreedzClimbing/hl2 folder that contains hl2_textures_* vpk files?

Originally posted by Raptor:

Could you confirm that you have a KreedzClimbing/hl2 folder that contains hl2_textures_* vpk files?

Correct, the files are there.
I could paste the whole hierarchy if it helps, but to my understanding it should all be there.

Recently I updated the game's engine to resolve some security issues, it's possible there's now a dependency on steam game settings when it comes to command lines (since hl2 uses command lines to determine which mod to load) and this is affecting Proton, just to be safe I've enabled steam command line processing now, please restart steam and see if it works!