I have a company. Our first employee (twenty years ago) had a serious MUD addiction. While a decent and hard-working fellow, he couldn't resist playing his MUD on the job. That was easy enough for him: one of his many terminals was dedicated to it and he would enter a command every few minutes or so. He got a couple of formal warnings before refraining from that behaviour (or he got better at hiding it). Before he came to work for us he had flunked university, and I am pretty sure MUD had to do with that. People who knew him before said he always hung out at the college computer club instead of attending courses.