Weird stuff with steam, proton, and filesystems

UPDATE: This can be a possible solution, but might not be what OP needs.

Wineprefixes don't work right on NTFS filesystems because some files contain colons, which is a reserved character in NTFS and FAT.

If you look inside the game's wineprefix, the dosdevices directory will typically have two symbolic links: one named c: that points to the drive_c directory, and another named z: that points to the filesystem root (plus a few others that are irrelevant). These will appear as lettered drives for programs running inside Wine. If the wineprefix is on an NTFS partition, those files can't be created because their names contain an invalid character.

You'll have to either relocate the wineprefixes to an ext4 or btrfs partition (I don't know if you can do that on Steam), or format the NTFS drive using ext4 or btrfs.

when I mount the drive through steam, I get a Polkit password prompt

It's not related to the issue, mounting a device usually requires elevated privileges. The same thing happens when it is mounted through fstab, except the process that mounts it already has elevated privileges. Access to the filesystem is not affected by this.

I've done my tests, and it looks like I may have been incorrect.

Point 1. While I was right to suspect the : character, I discovered that it is permitted in NTFS and only reserved in Windows. When an NTFS volume is mounted in Linux, it only becomes a problem if the windows_names option is used. Sometimes it is used, sometimes it isn't, and I don't know when.

Point 2. The other thing I found is that Wine only works if the wineprefix is owned by the user. NTFS doesn't understand Unix-style file ownership and permissions, so it must determine the uid, gid, and umask when the volume is mounted. When mounted with OP's fstab entry, it will default to root, so every file (including the wineprefixes) within the volume will appear as being owned by root, which prevents Wine from starting.

This might also explain why mounting the drive dynamically worked, as it probably used udisks2 to mount it as the user.

The solution may be as simple as specifying the uid and gid mount options. In a system with a single user, they should both be 1000, but you can check them by running echo $UID $GID.

The modified fstab entry should be:

UUID=E01A2CEC1A2CC180 /mnt/games ntfs nofail,uid=1000,gid=1000 0 3

This will present all files as being owned by the user, and should allow wine to run.

Point 3. That being said, mixing Windows and Linux is still not a good idea. I don't know what will happen if you create wineprefixes on NTFS. Windows might see the invalid filenames and shit itself. I tried doing it on a new NTFS volume and Windows wouldn't even mount it.

If you really want to keep the game files on the NTFS volume, you might have better luck trying your own symlink fuckery. If you have the Steam library on the NTFS device, you could try moving the .../SteamLibrary/steamapps/compatdata directory to a Linux filesystem, then creating a symlink in compatdata's place that points to the moved directory. This method moves the problematic files outside the volume.

The second method involves bringing the game files on the NTFS volume into the default Steam library on the Linux filesystem using a bind mount -- a way to mount a directory at a different mount point. In essence, this replaces the .../steamapps/common directory with that on the NTFS volume, and avoids creating wineprefixes inside the NTFS filesystem in the first place.

• Mount the NTFS volume using the fstab entry above.
• Assuming that you have the Steam stuff in their default locations, execute sudo mount --bind /mnt/games/SteamLibrary/steamapps/common ~/.local/share/Steam/steamapps/common to create the bind mount manually.
• Or use the equivalent fstab entry:

/mnt/games/SteamLibrary/steamapps/common /home/salty/.local/share/Steam/steamapps/common none defaults,bind 0 0

NTFS doesn't support symlinks, so it doesn't work correctly from NTFS partition. Also it is possible that you can corrupt those files on NTFS partition by doing that.

Basically don't mix Windows stuff with Linux stuff when running programs. It's okay for media.