Steam - Troubleshooting07 Oct 2018
Steam application hangs on startup
A single window is shown without any text on it and any signs of what is going on.
it has turned out Steam doesn’t play well with case-sensitive filesystems on macOS - doesn’t play at all to be precise.
one of the solutions is to create a separate case-insensitive APFS volume and move all Steam data (~/Library/Application Support/Steam/) to it:
$ diskutil apfs addVolume disk1 APFS Steam Exporting new APFS Volume "Steam" from APFS Container Reference disk1 Started APFS operation on disk1 Preparing to add APFS Volume to APFS Container disk1 Creating APFS Volume Created new APFS Volume disk1s5 Mounting APFS Volume Setting volume permissions Disk from APFS operation: disk1s5 Finished APFS operation on disk1 $ mv ~/Library/Application\ Support/Steam /Volumes/Steam/Library $ ln -s /Volumes/Steam/Library ~/Library/Application\ Support/Steam