The Talos Principal 2 demo is available in Steam now, the full game comes out in November.
https://store.steampowered.com/app/835960/The_Talos_Principle_2/
But since the games is officially Windows only, it won’t let me download/install the demo (because linux).
Why Steam?!?? You’re going to let me use Proton to play the full game sp why not allow the demo to run the same way?
If anyone knows a work-around I’d be very happy.
EDIT: The suggestion by @ECCTM worked very well and I’ve started playing the demo. It “just worked”.
SECOND EDIT: I started a new Community for discussing the whole Talos Principle series, for anyone interested.
Valve should consider making it the default at this point, and just give the user a warning the first time they launch a non-supported game. Because these issues happen often enough that people may be left with a bad impression of Linux (and Steam) game support.