going through the error logs, I found (proton 9.0-4):

33188.678:00d4:00d8:err:xrandr:xrandr14_get_adapters Failed to get adapters
...
33196.410:0138:0184:err:vulkan:init_vulkan Failed to load Wine graphics driver supporting Vulkan.
...
err:   DxvkInstance: Required instance extensions not supported
33196.416:0138:0184:err:winediag:nodrv_CreateWindow Application tried to create a window, but no driver could be loaded.
33196.416:0138:0184:err:winediag:nodrv_CreateWindow L"The explorer process failed to start."

And for ProtonGE10-32:

34536.003:0090:009c:err:ntoskrnl:ZwLoadDriver failed to create driver L"\\Registry\\Machine\\System\\CurrentControlSet\\Services\\winebth": c0000142
...
34545.627:0174:0178:err:kerberos:kerberos_LsaApInitializePackage no Kerberos support, expect problems
...
34545.637:0174:0178:err:ntlm:ntlm_LsaApInitializePackage no NTLM support, expect problems
...
34547.138:0174:01c8:err:winediag:nodrv_CreateWindow Application tried to create a window, but no driver could be loaded.
34547.138:0174:01c8:err:winediag:nodrv_CreateWindow L"The explorer process failed to start."
34547.138:0174:01c8:warn:seh:dispatch_exception backtrace: --- Exception 0xc0000005.
...
34547.898:011c:014c:err:service:device_notify_proc failed to get event, error 1726

Uploading my log file generated with PROTON_LOG=1.

Excerpts of particular note:

warn:  OpenXR: Unable to get required Vulkan instance extensions size
1295.073:0134:0180:err:vulkan:init_vulkan Failed to load Wine graphics driver supporting Vulkan.
1295.073:0134:0180:err:vulkan:init_vulkan Failed to load Wine graphics driver supporting Vulkan.
info:  Required Vulkan extension VK_KHR_surface not supported

err:   DxvkInstance: Required instance extensions not supported
1295.079:0134:0180:err:winediag:nodrv_CreateWindow Application tried to create a window, but no driver could be loaded.
1295.079:0134:0180:err:winediag:nodrv_CreateWindow L"The explorer process failed to start."

steam-4254230.log

I can launch the game, if a use protontrick to change wine setting to use "alldlls=builtin'.
but i have a error message "W:12:00000057" (it's probably the anti-cheat)

GE-Proton10-32
AMD Radeon RX 9070 XT

https://marathonstatus.com/errors.php states:

Platform-Specific Issues

PC — Linux / Steam Deck

BattlEye anti-cheat blocks Proton. No workaround available.

Replying to https://github.com/ValveSoftware/Proton/issues/9532#issuecomment-3972100137

that information is incorrect, battleye supports proton. it is up to the game studio to enable it or not by contacting battleye and valve.

https://partner.steamgames.com/doc/steamdeck/proton

idk where they got that information as bungie has not said that marathon is blocking proton on purpose.

Edit: if you check the main game steam store page valve has marked the game as unsupported because anticheat is not setup for steamdeck/Linux properly.

Replying to https://github.com/ValveSoftware/Proton/issues/9532#issuecomment-3972112112

Honestly, there is a bit of speculation on what im going to say, but I remember some devs saying that BattlEye silently removed proton support due to being Userspace, those developers sended email request to BE for enabling AC and got radio silent and a deny after, if i can remember where I found that, will quote it here, but also its speculation.

I wouldn't be surprised if BattlEye removed Proton support at one point tho, they really moved onto Kernel AC territory

https://github.com/ValveSoftware/Proton/issues/9532#issuecomment-3970847746
I was able to replicate on ProtonGE but not Proton Hotfix or Experimental. The fact we get a render window suggests the graphics DLLs that ship with Marathon may need masking. The ant-cheat DLLs may need to be unmasked if they're masked by alldlls=builtin, the error window suggests this.

Am I correct in understanding this should override all DLLs?
This is the list made by running find -type f -name "*.dll" | sed -e 's/.dll//' -e 's@.*/@@' | tr '\n' ',' in the Marathon Server Slam directory for Steam. Using WINEDLLOVERRIDE="[...],b" should cause it to only use WINE .dll shims for all the DLLs in the game path?

WINEDLLOVERRIDE="dbghelp,SharpDX,d3dcompiler_47,SharpDX.DXGI,vcruntime140,opus,opusenc,d3d12core,oo2core_9_win64,libxell,zlib1,WinPixEventRuntime,libcurl,GFSDK_Aftermath_lib.x64,nvngx_dlss,d3d12sdklayers,steam_api64,fvad,amd_fidelityfx_upscaler_dx12,libtox,amd_fidelityfx_loader_dx12,PartyWin,libxess,BEClient_x64,vcruntime140_1,msvcp140=b" PROTON_LOG=1 %command%

[#9532 (comment)](https://github.com/ValveSoftware/Proton/issues/9532#issuecomment-3970847746) I was able to replicate on ProtonGE but not Proton Hotfix or Experimental. The fact we get a render window suggests the graphics DLLs that ship with Marathon may need masking. The ant-cheat DLLs may need to be unmasked if they're masked by alldlls=builtin, the error window suggests this.

Here's what I tried, it gets to the login animation but then crashes. Same result as I get with alldlls=builtin, but with a less nuclear selection of overrides. I posted it on the discord, but I'm posting it here too in case it helps.

• Proton version doesn't seem to matter, the behaviour is consistent across 9, 10, experimental, hotfix and ge-26.
• I have the Steam overlay disabled and LD_PRELOAD="" since I was getting some errors about that.
• I have the BattlEye Runtime installed in Steam, but as the devs have not enabled support it's not really doing anything at the time of writing. You will need to adjust the path to fit where your install is at since it's going to be different from mine.

WINEDLLOVERRIDES="vcruntime140.dll=b;vcruntime140_1.dll=b;msvcp140.dll=b;d3dcompiler_47.dll=b" PROTON_BATTLEYE_RUNTIME="/home/lain/Games/Steam/steamapps/common/Proton BattlEye Runtime/" LD_PRELOAD="" PROTON_LOG=1 %command%

Sadly, until they enable support I think this is about as far as we're going to get.

Replying to https://github.com/ValveSoftware/Proton/issues/9532#issuecomment-3973892126

It launches for me without crashing with the WINEDLLOVERRIDES when using proton-cachyos-10.0-20260207 slr

Once the game starts logging in I do see this screen:

W:12:00000057

I made a post requesting more information on what this error means: https://help.marathonthegame.com/hc/en-us/community/posts/46728212894228-Error-W-12-00000057

I've been trying to get it to work better without much luck. But they just pushed an update on Steam and it now launches without any launch options required now for me on Proton cachy slr. Still can't login but it doesn't crash.

Doesn't 0x57 in Windows translate to "invalid parameter"? Enabling logging in Proton and looking through it, I see a few interesting things. I don't believe Marathon is blocking Linux explicitly, but it's requiring something in the HTTP stack that Proton doesn't seem to currently implement.

request_query_option unimplemented option 147

Above is what proton is currently throwing after the SSL Handshake when trying to sign in. Researching what 147 is, I came across WINHTTP_OPTION_SERVER_CERT_CHAIN_CONTEXT. Would like to hear more thoughts on this. To me, it seems like a missing WinHTTP feature. Or it's BattleEye, I'm wrong, and this is just collateral damage.

EDIT: Never mind, I might just be dumb.

It seems that my previous statement may have been for telemetry only. The game is loading libcurl.dll; I'm assuming it's going to use libcurl -> schannel for https. Grep'ing for those events during login, I find the following.

gnutls_log <3> ASSERT: ... buffers.c[_gnutls_io_read_buffered]
gnutls_log <3> ASSERT: ... record.c[_gnutls_recv_int]
schan_DecryptMessage Received 256 bytes
DeleteSecurityContext ...
FreeCredentialsHandle ...

It seems for some reason GnuTLS/Schannel is unhappy.

Well, I think I found... something? Bungie responded, although I'm unsure whether can we treat it as a "that's it" answer.

https://help.marathonthegame.com/hc/en-us/community/posts/46686059960596-Unable-to-Launch-on-Linux
https://help.marathonthegame.com/hc/en-us/community/posts/46685301449620-Unable-to-launch-on-Steam-Deck

I don't think the support person counted in Proton though.

Well, I think I found... something? Bungie responded, although I'm unsure whether can we treat it as a "that's it" answer.

https://help.marathonthegame.com/hc/en-us/community/posts/46686059960596-Unable-to-Launch-on-Linux
https://help.marathonthegame.com/hc/en-us/community/posts/46685301449620-Unable-to-launch-on-Steam-Deck

I don't think the support person counted in Proton though.

Those are also me...so far from my interactions with Bungie Support haven't been the most helpful.

Manually running the BattlEye installer results in the following: Failed to install BattlEye Service (5, 424).

The game opens fine using GE-Proton10-32, and shows the error W:12:00000057 after trying to log in.

Irrelevant now the server slam is closed and moved to new issue linked above.