Hi!

I got the game running on Bazzite, but it took a few workarounds. Summary for the devs first, then the details and a step-by-step fix for other Linux players.

Suggestions for the devs

Exclude libwayland-* from the AppImage at build time. The bundled copies cause a blank white launcher window on up-to-date distros. Other Tauri projects have fixed it the same way.
Clear PYTHONHOME, PYTHONPATH and LD_LIBRARY_PATH before spawning umu-run. The launcher’s AppImage environment leaks into the system’s umu-run and breaks its Python, so the game can’t start.
Consider installing the game outside the AppImage directory. The game files currently appear to end up in squashfs-root/usr/bin/mnm/, which is read-only when the AppImage runs normally and gets lost when the launcher is replaced.

Bug 1: blank white launcher window
Terminal output:

Could not create default EGL display: EGL_BAD_PARAMETER. Aborting...

The AppImage bundles its own libwayland-* libraries (a WebKitGTK dependency), and they conflict with the newer graphics stack on up-to-date distros. This is a known Tauri/AppImage issue. Setting WEBKIT_DISABLE_DMABUF_RENDERER=1, WEBKIT_DISABLE_COMPOSITING_MODE=1 or GDK_BACKEND=x11 did not help.

Bug 2: Play fails, umu-run crashes
The launcher passes its AppImage environment to the system’s umu-run. The host Python then fails one step after another:

Fatal Python error: Failed to import encodings module
ModuleNotFoundError: No module named 'umu'
Can't connect to HTTPS URL because the SSL module is not available (so GE-Proton can’t be downloaded)

Workaround for players

1. Extract the AppImage and remove the bundled libwayland:

bash
mkdir -p ~/Games/MnM && cd ~/Games/MnM
/path/to/MonstersAndMemories_amd64.appimage --appimage-extract
find squashfs-root -name 'libwayland-*' -print -delete

2. Create a wrapper so umu-run gets a clean environment:

bash
mkdir -p ~/.local/bin
cat > ~/.local/bin/umu-run <<'EOF'
#!/bin/bash
unset PYTHONHOME PYTHONPATH LD_LIBRARY_PATH LD_PRELOAD GIO_MODULE_DIR
exec /usr/bin/umu-run "$@"
EOF
chmod +x ~/.local/bin/umu-run

3. Test from a terminal with the wrapper first in PATH:

bash
cd ~/Games/MnM/squashfs-root
PATH="$HOME/.local/bin:$PATH" ./AppRun

On first Play, umu downloads GE-Proton and sets up the prefix, and then the game starts.

Create a start script for Steam or your desktop:

bash
cat > ~/Games/MnM/start-mnm.sh <<'EOF'
#!/bin/bash
export PATH="$HOME/.local/bin:$PATH"
cd "$HOME/Games/MnM/squashfs-root"
exec ./AppRun
EOF
chmod +x ~/Games/MnM/start-mnm.sh

In Steam, add start-mnm.sh as a non-Steam game. If it doesn’t show up in the file picker, switch the file type to “All files”, or add any program and change the Target in Properties. Keep Proton off, since the launcher is a native Linux app. No launch options are needed.

Note: don’t delete squashfs-root when updating the launcher, since the game files are inside it. Extract the new version separately and move usr/bin/mnm/ over.

Thanks for supporting Linux! 🐧