Purchased Hacknet on GoG and it failed to start on macOS High Sierra v10.13.6, supposedly due to having System Integrity Protection turned on, which is a good thing.

Turns out, it was possible to play the game after a little ...hacking.

$ cd /Applications/Hacknet/Hacknet.app/Contents/MacOS/  # Go to Game Directory
$ cat Hacknet   # Shows the script to start it
$ chmod u+x Hacknet.bin.osx  # Make it executable

From then on out it's just:

$ cd /Applications/Hacknet/Hacknet.app/Contents/MacOS/
$ export DYLD_LIBRARY_PATH=$DYLD_LIBRARY_PATH:./osx/
$ MONO_DEBUG=explicit-null-checks ./Hacknet.bin.osx