Most Steam games launch briefly and then close on Linux Mint

Try installing Steam through Mint's recommended package with `sudo apt install steam-installer` rather than relying on the Flatpak. Flatpak can work, but its sandbox sometimes interferes with game libraries, drives, or required runtimes. Also collect a Proton log and a system report so the actual failure message can be identified.

First, check where the games are installed and what filesystem that drive uses. Games on an NTFS partition or an unusual secondary-drive setup can cause Proton permissions and launch problems. The exact game titles would also help, since some need specific launch options or Proton versions.

For a game that is failing, open its Properties, go to Compatibility, enable the option to force a compatibility tool, and test a stable Proton release such as Proton 9.0-4. Some games behave better when the native Linux version is bypassed and the Windows build is run through Proton instead.

GE-Proton is worth testing for titles that do not work with the standard versions. It includes additional patches and media components, although it is not a universal fix. Compare the game's requirements and known compatibility notes with your terminal output, and make sure the graphics drivers and 32-bit libraries are installed correctly.