It's curious that even calling the game from the flatscreen with VR off makes steam hang. This might not have to do with VR but the way the game initializes, I guess?
So, I've tested with an older kernel -- 6.16.11 -- to ensure it's not something from the very recent kernel I'm using and the same issue appeared. Next step is trying on a different graphical card.
Bingo. This does not happen on NVIDIA. So it's a bug in Mesa. How to report it, though?
proton 10.0-3x1 2026-01proton 8.0-5x1 2026-01
Compatibility Report
System Information
I confirm:
Symptoms
Game doesn't start, instead it seems to hang steam flatscreen interface (the VR interface continues responding). The game never appears in the VR headset and with proton 10.0-3 and experimental it opens up an invisible window in the flatscreen -- on proton 8.0-5 it at least makes the flatscreen go black, but still doesn't start. The proton processes running
Tentacular.exeare there but they seem to be unresponsive. The only way to get steam to recover and start responding again is by making the game exit forcefully from the VR interface.Reproduction
Install the game, connect to VR and from SteamVR, press play.
Notes
the log is for Proton 10.0-3, if you need logs for any other version just let me know.
steam-1220100.log