I made one in the mid 90’s, with the /etc/issue saying: root password is PASSWORD
ok PASSWORD wasn’t the actual password, I forget now what it was, but it literally was in /etc/issue as plain ascii text, so it was trivial to “root” the box! :)
It worked out really well for a few years, until script kiddies eventually found it and kept erasing everything, so I shut it down. Yes, the machine was accessible on the public internet with a DNS name. It was hosted at the local ISP I helped run.
It was a great little community, the hostname was never publicly posted saying it was open to the public, but through word of mouth or via curious people that would see the hostname and go huh, what’s that machine do! :)
Had maybe 100 users on it, before it died.