Compatibility Report

• Name of the game with compatibility issues: Ultrakill
• Steam AppID of the game: 1229490

System Information

• GPU: RTX 3080 Ti Max-Q
• Video driver version: NVIDIA 560.35.03
• Kernel version: 6.9.3-76060903-generic
• Link to full system information report as Gist: https://gist.github.com/BugsyReportsy/523d2435c923b49d6842690f5e97e2b4
• Proton version: Experimental, any version

I confirm:

• [x] that I haven't found an existing compatibility report for this game.
• [x] that I have checked whether there are updates for my system available.

Symptoms

When I try to launch Ultrakill with any version of Proton, the game would freeze a few seconds after launch. The only way to fix this is to delete the game's compatdata folder and sometimes to verify the integrity of the installed files afterwards. This has occured repeatedly and frequently within the past 2 months regardless of what OS I'm using. I've played on Endeavour OS, Linux Mint, and Pop!_OS, where I had the exact same issue and workaround. So far I have only experienced this issue often with Ultrakill and less often with games that don't officially support Proton such as Ultimate Admiral: AoS, since Deadlock doesn't have the same problem despite using Proton Experimental.

Reproduction

1. Launch Ultrakill after having previously played/launched a different Steam game which either uses Proton or Linux Runtime, TF2 or Deadlock for my specific case.
2. Expect Ultrakill to freeze a few seconds after launch, expect it to be a 50% chance.