A good idea is to check https://www.protondb.com/ to check which Proton version works with X game.
Some games works with earlier version and not later version. You can set up in Steam different Proton version per game.
Yes same here, no matter what i try to do it always says "launch failed". Installing the older protondb manually does not get picked up by steam either.
i was wondering ...
How did you install Steam? .deb/flat/snap? There can be a problem if you installed Steam as flat/snap as they run in sandbox.
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Just like what I experienced with FlatPak OnlyOffice.
It is in the sandbox and unable to connect a network printer nor a network drive. It is puzzling why they bother to create this mode of installation. Office suite without printer is completely useless 
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I didn't touch anything in the Software settings, so I guess FLAT since it's what it's set by default... (so no .deb)
I think you install flat then.
Both of you, try uninstall steam and go for .deb version.
Source in the appstore says flathub indeed
Should I save/move the games before uninstalling Steam or better download them again?
You could try move them (I've never done that before so...), if it doesn't work you can always delete and download again.
I installed the steam.deb and installed the proton, now it does show in steam.
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@Storm OMG it works! Thank you so much, been 10 days since Launch Day I couldn't find out why Proton wouldn't allow me to play on version 5.10+. I still don't know why (do you know what changed before version 5.10 and after?), but at least now I don't have to try so many workarounds and waste hours.
So, installing .deb worked.
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Flat/Snap is ... how should I put it ... problematic in many ways. So I always go for .deb or PPA's
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It wasn't my thread, I hopped into this one since it was Steam/Proton related 
Ah, OK.
I had to scroll up more 
Hello. I wondering also but in Store Software in Zorin is flat on photo.
that means when installing something is best using .deb packs?
For steam .deb is best. You'll find it at steam homepage.
