Compatibility Report

With Proton 6.8 GE-1 the launcher shows, successfully checking/downloading an update, but it fails to actually launch the game, only shows a popup window for a brief moment then instantly crash.
steam-1368910.log

with wined3d / PROTON_USE_WINED3D it can launch the game, but it is unstable and always crashes at some point.
steam-1368910-wined3d.log

I found a solution that makes this game work and prevents crashing.

1. Use vanilla Proton 5.0-10 (Proton 6 seems to have breakages)
2. Run the following command sudo ln -s /home/$USER/.steam/ /home/$USER.steam
3. Use PROTON_USE_WINED3D=1 as @rezzafr33 specified.

Good luck.

Wow thank you @B3HOID it works, can you explain to me why is the symlink necessary? It seems to fix the launcher, I don't understand how.

UPDATE (should have replied instead updating :D ):
~I am able to use DXVK if I override dxgi to builtin with WINEDLLOVERRIDES="dxgi=b", but don't activate DXVK_HUD or it won't be able to launch, I still can use mangohud though.~ It a hit and miss, sometimes it works, sometimes it doesn't.

~I also try to switch to Proton 5.13 and it also works.~ better to stay at 5.0-10

Wow thank you @B3HOID it works, can you explain to me why is the symlink necessary?

I think it's because of the path in which the game installs updates to, not sure though.

Got another problem, the launcher.exe only starts if I launch steam from the terminal. At least I and one other person got this problem

As a workaround, we wrap the command with xterm
PROTON_USE_WINED3D=1 xterm -T "Super Mecha Champions - Launcher" -e "gamemoderun mangohud %command%"

Hello,
I managed to get the game running with DXVK just fine. It works only with 5.0-10 and takes up to 5 or 6 times upon trying to get it running(usually 3-4 launches should get you running just fine). However it requires you to make DXVK conf file with the following:
dxgi.deferSurfaceCreation = True
d3d9.deferSurfaceCreation = True
then use a launch command to link to it : DXVK_CONFIG_FILE=/path/to/config.conf %command%
but you'll also need to start it with terminal so for me it's konsole -e
the final command I use is this: DXVK_CONFIG_FILE=/path/to/config.conf konsole -e %command%
with Proton 5.0-10, it takes a couple of times launching to get it sometimes or if you are lucky enough you'll get in from first try, but up to 5 maximum 6 times from what I've tested. It's fairly consistent.
EDIT: In case someone wants better performance - the latest as of now Proton 6.14 GE 2 seems to work with PROTON_USE_WINED3D=1 which actually gives higher performance than dxvk, but very unstable, however one can try to use zink(OpenGL on Vulkan) with the mesa package installed(works on Nvidia too) with this command: MESA_LOADER_DRIVER_OVERRIDE=zink PROTON_USE_WINED3D=1 %command%