Hello @8rgvgz7z9c-sudo, we're using one issue report per unofficially supported game title, so I've gone ahead and transferred this issue report to https://github.com/ValveSoftware/Proton/issues/8568#issuecomment-5453058602.
proton experimentalx1 2026-08PROTON_LOG=1x1 2026-08PROTON_NO_ESYNC=1x1 2026-08PROTON_NO_ESYNC=1 %command%x1 2026-08mf.dllx1 2026-08
Compatibility Report
Name of the game with compatibility issues: The First Berserker: Khazan
Steam AppID of the game: 2680010
System Information
Symptoms
The game no longer launches on Steam Deck.
When pressing Play, Steam briefly shows that the game is starting, but the game does not launch and returns to the Steam library.
The issue occurs with multiple Proton versions:
I also verified the integrity of the game files, but this did not resolve the issue.
I additionally tested:
PROTON_NO_ESYNC=1 %command%
with no change.
Reproduction
Proton log
The attached steam-2680010.log shows an EXCEPTION_ACCESS_VIOLATION involving mf.dll shortly after Vulkan initialization.
Relevant error:
EXCEPTION_ACCESS_VIOLATION
mf.dll + 0x34243
The attached Proton log was generated using:
PROTON_LOG=1 %command%
Additional information
The game previously worked correctly on this Steam Deck, so this appears to be a regression or compatibility issue rather than an initial installation problem.
Game files have been verified through Steam.
steam-2680010.log