Compatibility Report

• Name of the game with compatibility issues: CPM 2
• Steam AppID of the game: 4252340

System Information

• GPU: AMD Radeon RX 7800 XT
• Video driver version: Mesa 25.1.1
• Kernel version: Linux 6.14.6-106.bazzite.fc42.x86_64
• Link to full system information report as Gist: https://gist.github.com/sraaronrock/eacd25027fb8be284e9eb7c66c583670
• Proton version: Proton 11 & Proton 9.0.4

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.

Symptoms

On desktop Linux the Steam client ships no Linux content for this app and does not
fall back cleanly, even though the app advertises a native Linux launch option.
Content that exists only as a steamdeck: 1 Linux depot is skipped by the desktop
client; the app is installed as the Windows depot and run through Proton, while the
Linux launch option is still offered but its executable is missing.

This is the same class of issue as [#12019](https://github.com/ValveSoftware/steam-for-linux/issues/12019)

Reproduction

1. On desktop Linux, install AppID 4252340 from the Steam client.
2. Observe that only depot 4252343 (Windows) is installed; steamapps/common/CPM2/
   contains the Windows build, no CPM2.x86_64.
3. Select the native launch option (CPM2.x86_64) -> "CPM2.x86_64 not found".
4. Launch the game -> it runs the Windows build via Proton (crashes immediately on my
   system, unrelated Wine/IL2CPP issue).