Compatibility Report

• Name of the game with compatibility issues: Fortress Forever
• Steam AppID of the game: 253530

System Information

• GPU: RX 580
• Driver/LLVM version: Mesa 20.3.5
• Kernel version: 5.10
• Link to full system information report as Gist: https://gist.github.com/hunteroone/81efb7c8337db396c5f9d14a87ba0ddf
• Proton version: Proton-Experimental & 6.3-5

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.

steam-253530.log

Symptoms

• Custom maps cannot be downloaded. Internet Explorer is needed (and cannot be installed due to 64-bit only prefix).
• On first startup, loading a server/training mode crashes the game if you set the resolution to something besides the default 4:3. It doesn't happen afterwards.

Reproduction

For the crash:

• Install the game
• Change 4:3 to 16:9 (I used 1920x1080)
• Join a server/training mode, it should crash

For the inability to download custom maps:

• Join a server that uses custom content after the initial crash
• Any custom maps will not be downloaded, whereas it will on Windows.