While it should not be necessary, it is possible (with a bit of symlinking) to get Steam on OS X working with a case-sensitive boot volume.

This can be done as follows:

No problem with the update for my iPhone and iPad but massive problems with the latest Mojave update on my Mac! Still not fixed after spending four hours with the Apple help line running many programs trying to fix with no success.Now they are planning to reset my whole computer from my backup hardrive.this morning.fingers crossed that works. 'Case-sensitive Journaled HFS' (hard drive IS case-sensitive), or 'Journaled HFS' (hard drive is NOT case-sensitive) For advanced users familiar with Unix and Terminal, you may be able to get your case-sensitive system to work by using symbolic links. Restart your Mac, and then hold down Command-R before the Apple logo appears to bring up macOS Recovery. Click Disk Utility in the list of options that appears. Select the internal drive or boot. In computers, case sensitivity defines whether uppercase and lowercase letters are treated as distinct (case-sensitive) or equivalent (case-insensitive).For instance, when users interested in learning about dogs search an e-book, 'dog' and 'Dog' are of the same significance to them.

1. Launch Disk Utility, and create a new disk image (File > New > Blank Disk Image…).
   I used the following options:
   • Name: Case Insensitive
   • Size: 100 GB
   • Format: Mac OS Extended (Journaled)
   • Partitions: Hard Disk
   • Image Format: sparse bundle disk image
2. In your new case-insensitive volume (mine is named “Case Insensitive”, so all paths used in this document will refer to it as such), create the following directories:
   • /Applications
   • /Home
   • /Home/Library/Application Support/Steam
   • /Home/Documents/Steam Content

   NOTE: These paths are suitable for a single user. I chose to use /Users/dustin/…

3. Download Steam and put Steam.app in /Volumes/Case Insensitive/Applications
4. Symlink your Steam directories to the case-insensitive volume. In Terminal:
   

   ln -s /Volumes/Case Insensitive/Home/Library/Application Support/Steam ~/Library/Application Support/Steam
   ln -s /Volumes/Case Insensitive/Home/Documents/Steam Content ~/Documents/Steam Content

5. Create /volumes (lowercase) and symlink /Volumes/Case Insensitive into it as “case insensitive”. This is to get around the intentional lowercasing Steam does of all paths it comes into contact with.
   

   mkdir /volumes
   ln -s /Volumes/Case Insensitive /volumes/case insensitive

6. Launch Steam!

If that’s too much work, use this shell script. Save it to your home directory (or wherever, really), launch Terminal, and issue the following commands:

chmod +x ~/steamcase.sh
~/steamcase.sh 100g

How To Fix Case Sensitive Problem For Macbook

Substitute 100g with your desired size. This script creates a sparse bundle disk image, so you don’t need to worry about having all 100 GiB (or whatever size you choose) available up-front.
Then proceed to install Steam.app to /Volumes/Case Insensitive/Applications. Run and enjoy!

How To Fix Case Sensitive Problem For Mac Pro

Honestly, Valve, this shouldn’t even be necessary.