SOLVED: Installed GloriousEggroll custom Proton. For Talos, also had to set launch options (PROTON_ENABLE_NVAPI=1 PROTON_LOG=1 %command%) or else I'd just get a black screen. First runs of games take a bit to get loaded, but launch without issue on subsequent runs.

I'm a recent convert to Linux - currently running Mint 21.2. I don't have a huge Steam library and thankfully most of the handful of games I play have worked fine - Deep Rock, Lethal Company, Sea of Thieves, Elite Dangerous (although that one is through Epic, thanks Heroic Launcher).

Two others that I've tried so far - Astroneer and Talos Principle II - don't seem to want to get started. When I hit play on either of those in Steam, it just stalls at "Launching..." I can cancel the launching and it'll go back to the Play button, but at this point Steam won't launch anything else. When I try to exit steam, the main window closes but its icon is still in the system tray icons. At this point, I have to kill the steam tasks before I can get it to re-open.

Since I'm seeing similar behavior for two different games, I'm guessing it might have something to do with the Proton config? I don't know much about it other than it being the main compatibility layer that gets the games running on Linux. In my Steam compatibility settings, I've got Steam Play enabled for supported and all other titles, and I've got "Run other titles with" set to Proton Experimental. I've seen that you can set the Proton version on a per-game basis as well. If that's the issue, is it just trial-and-error figuring out which version I need to use with each game?