

It could be that your specific hardware has some quirk about it which is not properly taken into account by the latest Proton…
My GPU is GeForce 1070 and I naturally use Nvidia’s Linux drivers. My CPU is AMD Ryzen 7 1700. So I highly doubt my hardware is quirky in any way.
I changed my client to a beta version and enabled the new experimental SteamRT3 Steam Client, as suggested. I have not enabled the Steam Overlay.
Does Proton 9 work?
Here’s what happens:
Proton 9 results
Adding process 228862 for gameID 460810
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
wine: using kernel write watches, use_kernel_writewatch 1.
Adding process 228877 for gameID 460810
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
wine: using kernel write watches, use_kernel_writewatch 1.
Adding process 228885 for gameID 460810
wine: using kernel write watches, use_kernel_writewatch 1.
[2026-06-15 01:01:45.033] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.config/MangoHud/wine-explorer.conf' [ not found ]
[2026-06-15 01:01:45.033] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.steam/debian-installation/steamapps/common/Proton 9.0 (Beta)/files/bin/MangoHud.conf' [ not found ]
[2026-06-15 01:01:45.033] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.config/MangoHud/wine64-preloader.conf' [ not found ]
[2026-06-15 01:01:45.033] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.config/MangoHud/MangoHud.conf' [ not found ]
sh: 1: glxinfo: not found
[2026-06-15 01:01:45.354] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.config/MangoHud/wine-explorer.conf' [ not found ]
[2026-06-15 01:01:45.354] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.steam/debian-installation/steamapps/common/Proton 9.0 (Beta)/files/bin/MangoHud.conf' [ not found ]
[2026-06-15 01:01:45.354] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.config/MangoHud/wine64-preloader.conf' [ not found ]
[2026-06-15 01:01:45.354] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.config/MangoHud/MangoHud.conf' [ not found ]
sh: 1: glxinfo: not found
[2026-06-15 01:01:45.584] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.config/MangoHud/wine-explorer.conf' [ not found ]
[2026-06-15 01:01:45.584] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.steam/debian-installation/steamapps/common/Proton 9.0 (Beta)/files/bin/MangoHud.conf' [ not found ]
[2026-06-15 01:01:45.584] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.config/MangoHud/wine64-preloader.conf' [ not found ]
[2026-06-15 01:01:45.584] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.config/MangoHud/MangoHud.conf' [ not found ]
sh: 1: glxinfo: not found
[2026-06-15 01:01:45.926] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.config/MangoHud/wine-explorer.conf' [ not found ]
[2026-06-15 01:01:45.926] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.steam/debian-installation/steamapps/common/Proton 9.0 (Beta)/files/bin/MangoHud.conf' [ not found ]
[2026-06-15 01:01:45.926] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.config/MangoHud/wine64-preloader.conf' [ not found ]
[2026-06-15 01:01:45.926] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.config/MangoHud/MangoHud.conf' [ not found ]
sh: 1: glxinfo: not found
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
wine: using kernel write watches, use_kernel_writewatch 1.
Adding process 228961 for gameID 460810
wine: using kernel write watches, use_kernel_writewatch 1.
Setting breakpad minidump AppID = 460810
Steam_SetMinidumpSteamID: Caching Steam ID: 76561198052811166 [API loaded no]
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt64/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS64): ignored.
ERROR: ld.so: object '/tmp/pressure-vessel-libs-K54fyC/${LIB}/libMangoHud.so' from LD_PRELOAD cannot be preloaded (cannot open shared object file): ignored.
wine: using kernel write watches, use_kernel_writewatch 1.
Adding process 228980 for gameID 460810
Fossilize INFO: Overriding serialization path: "/home/quentin/.steam/debian-installation/steamapps/shadercache/460810/fozpipelinesv6/steamapprun_pipeline_cache".
pid 228821 != 228820, skipping destruction (fork without exec?)
Game Recording - game stopped [gameid=460810]
Removing process 228980 for gameID 460810
Proton 10
Adding process 234540 for gameID 460810
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
Adding process 234673 for gameID 460810
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
Adding process 234678 for gameID 460810
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
fsync: up and running.
Adding process 234679 for gameID 460810
Adding process 234680 for gameID 460810
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
Adding process 234684 for gameID 460810
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
Adding process 235015 for gameID 460810
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
Adding process 235018 for gameID 460810
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
Adding process 235028 for gameID 460810
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
Adding process 235035 for gameID 460810
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
Adding process 235042 for gameID 460810
[2026-06-15 01:09:51.430] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.config/MangoHud/wine-explorer.conf' [ not found ]
[2026-06-15 01:09:51.430] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.steam/debian-installation/steamapps/common/Proton 10.0/files/bin/MangoHud.conf' [ not found ]
[2026-06-15 01:09:51.430] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.config/MangoHud/wine64-preloader.conf' [ not found ]
[2026-06-15 01:09:51.430] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.config/MangoHud/MangoHud.conf' [ not found ]
sh: 1: glxinfo: not found
[2026-06-15 01:09:51.498] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.config/MangoHud/wine-explorer.conf' [ not found ]
[2026-06-15 01:09:51.498] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.steam/debian-installation/steamapps/common/Proton 10.0/files/bin/MangoHud.conf' [ not found ]
[2026-06-15 01:09:51.498] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.config/MangoHud/wine64-preloader.conf' [ not found ]
[2026-06-15 01:09:51.498] [MANGOHUD] [info] [config.cpp:118] skipping config: '/home/quentin/.config/MangoHud/MangoHud.conf' [ not found ]
sh: 1: glxinfo: not found
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
Adding process 235098 for gameID 460810
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/steamrt64/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS64): ignored.
ERROR: ld.so: object '/tmp/pressure-vessel-libs-68nGNM/${LIB}/libMangoHud.so' from LD_PRELOAD cannot be preloaded (cannot open shared object file): ignored.
Adding process 235118 for gameID 460810
Fossilize INFO: Overriding serialization path: "/home/quentin/.steam/debian-installation/steamapps/shadercache/460810/fozpipelinesv6/steamapprun_pipeline_cache".
pid 234682 != 234680, skipping destruction (fork without exec?)
Game Recording - game stopped [gameid=460810]
Removing process 235118 for gameID 460810
And pretty much the same for Proton-GE 10-34.


I installed System76’s Nvidia drivers, but then my second display couldn’t work, and I read online that it’s a common problem. Then I manually installed Nvidia’s closed source driver instead, and now my second display works all fine.
EDIT: Now the game booted!