Proton: Spacebourne (732240) fails with "Fatal Error" (Unreal 4 Engine)

[Patola]

Compatibility Report

• Name of the game with compatibility issues:
  Spacebourne, an early-access RTS/FPS hybrid.
• Steam AppID of the game: 732240

System Information

• GPU: NVIDIA GTX 1070
• Driver/LLVM version: NVidia 430.26
• Kernel version: 4.15.0-54-lowlatency
• SO: Ubuntu 18.04 with all updates

• gist of system information: https://gist.github.com/Patola/d4079846a097d990b768a218b245caf7

• Proton version: 4.2-9

I confirm:

• [X] that I haven't found an existing compatibility report for this game.
• [X] that I have checked whether there are updates for my system available.

log file:
steam-732240.log

Symptoms

Doesn't start: clears the screen blank then after a few seconds shows a "Fatal Error!" dialog where you can only press OK. Using wmctrl -l I could see that the title of that dialog was "The UE4-ASPv3 Game has crashed and will close".

Reproduction

1. Install the game, then try to start it.

[Patola]

Tried most of proton variables, like PROTON_USE_WINED3D=1 and PROTON_NO_ESYNC=1 to no avail. Same error. With PROTON_NO_D3D11, the game doesn't even blank the screen.

Also, sent a compatibility status to protondb, saying it's borked. And commented on the Linux support steam thread of the game, https://steamcommunity.com/app/732240/discussions/0/1742216566127593383/?ctp=4

[Corben78]

Looking into the log file it might be related to mfplat.dll. So maybe using the workaround to install the media foundation dlls (https://github.com/tonix64/python-installcab) and placing a mfplat.dll into the games directory might help.

[byte1024]

The current last few versions of wine have some Media Foundation fixes in them. Just maybe it will work then but Proton isn't yet using those versions. They might also need to add some more fixes in.

Installing anything involving Windows media with newer games will typically be futile.

[kisak-valve]

Hello @rsw0x, the workaround you posted is legally problematic and has been removed.

[Patola]

@kisak-valve but for those who bought the game it is precious.
However now the game gives "Fatal Error" when starting even with the workaround...

[Patola]

This is the logfile with the workaround, with the Fatal Error dialog. It blanks the screen and waits a few seconds then gives this Fatal Error.
steam-732240.log

[Patola]

Reinstalled the game and used "that workaround" again. Then it worked.