Hello @daggintosh, these look like some lines of interest from your Proton log:
err:vrclient:create_win_interface Don't recognize interface name: IVRSystem_007
err:vrclient:ivrclientcore_get_generic_interface Failed to create win object IVRSystem_007.
If my memory serves me correctly I attributed that to the ancient steamvr unity package used when I looked into it a few years ago.
I found a mention of IVRSystem_007 in vrclient_x64
I'm guessing this is definitely a version compatibility issue since this number is incremented every openvr release.
quick fire edit, sorry
cppIVRSystem_IVRSystem_007 is skipped in that list of files in vrclient as well
Seems like this is occurring because:
As was expected, I was able to get everything working with the exception of an output to the headset. I tried.
This should basically work with the just updated Proton Experimental bleeding-edge branch (see https://github.com/ValveSoftware/Proton/wiki/Proton-Versions#proton-bleeding-edge ).
For now that is only going to work with officially supported SteamVR (the present workaround for old interfaces not supporting Vulkan relies on some SteamVR's Openvr implementation details) . So far OpenComposite doesn't support that old interfaces at all.
Also the game seems to be tight on 32 bit address space, despite of added workaround (which allows it to render anything at all in HMD) it is still possible it will occasionally hang during area load (maybe depending on GPU and its driver).
Confirmed both titles are now working! Thank you so much!
proton experimentalx1 2025-09proton 10.0x1 2025-09
Compatibility Report
System Information
I confirm:
Symptoms
Application launches but does not find SteamVR, also occurs with the older HTC Vive tech demo, Surgeon Simulator VR: Meet the Medic (457420).
Latter title has a pop-up banner that the headset cannot be found, but this one (namesake of issue), just shows the main menu with the player in the ground.
Both applications use Unity 5.
steam-518920.log
Reproduction