A fix for this was applied to Proton 4.11-1. Please retest!
Thanks @aeikum . I have updated my post for 4.11
Just tried running the game, I get sound a window, and I can hear audio when I press buttons.
https://gist.github.com/DigitalDevilSummoner/d7a227765539daee04f9fd1d98d2be93
steam-702890.log

Same issue as @DigitalDevilSummoner. The game seems to run but I only see a black window. Tried all Runtime config options (NO_D3D11, NO_D3D10, WINED3D, etc. One at a time)
steam-702890.log
Black window is caused by anti-aliasing (MSAA, default) not working for 'window' and 'full window' modes. With anti-aliasing (off) the window modes render graphics okay. While 'fullscreen' renders okay with any option.
/steamapps/common/BBTAG/Save/bbconfigs.ini and change value iDisplayMode=2 (line 2). Upon next launch the graphics should render.I tried running the game with Proton 5.0-1 but it crashes and gives a "InitRenderer" error on startup.
steam-702890.log
Hello @DraconYale, can you test if PROTON_USE_WINED3D=1 %command% has an effect?
It gives the same error but after some seconds the game starts anyway, tried to enter a lobby but now the game freezes instead of crashing while listing the lobbies
steam-702890.log
Tried with Proton 5.0-7. The game starts loading, then crashes, but after some seconds it restarts itself and it's playable offline. The occasional freeze caused by the lobby list still persists.
(I'm still starting the game with PROTON_USE_WINED3D=1 %command%)
steam-702890.log
This game works now, but only the first controller is detected with steam input.
proton 5.0-7x1 2020-05proton 5.0-1x1 2020-02proton 4.11-1x2 2019-07PROTON_USE_WINED3D=1x2 2020-05PROTON_USE_WINED3D=1 %command%x2 2020-05
Compatibility Report
System Information
Symptoms
Occasionally crashes when listing multiplayer lobbies quickly.
Reproduction
Run BBTAG.exe with Steam Play and Proton
4.2 log: steam-702890.log4.11-1 log crash:
steam-702890-updated.log
4.11-1 log working: ( launched into multiplayer lobby )
steam-702890.log
Additional Information
This may relate to Blazblue Central Fiction (586140) too as the same render error was posted there.4.2 error:fixme:d3d9:d3d9_device_CreateRenderTargetEx stub!Progress
4.2 error was patched in 4.11-1. This was merged into Proton 4.11-1 as 2b3955e
Using protonfixes with a winetrick for quartz removes one of the errors in the log.The game runs. The offline modes and multiplayer lobby seems to work (regardless of quartz). Game occasionally crashes when listing multiplayer lobbies (especially if done quickly).