I was having trouble figuring out how to join. From https://mdhughes.itch.io/mudhole I followed the link to http://cyberhole.online:8080/cyberhole/mudhole/MudholeHelp.html and thence to https://cyberhole.online/mudhole/. But that one didn’t let me create an account—it just responded null.
http://cyberhole.online:8080/cyberhole/mudhole/ is the URL I should have been using. That’s where I was able to create an account and found some other users already in the world.
Nice, evocative room and exit descriptions!