My main MUD was Discworld MUD which was started in 1991. I can't describe the excitement I felt on finding a game where the world continued when I was offline. Where I could go to make friends with the thrill of also making enemies.
It was the perfect place to escape to, which taught me about addiction and many aspects of myself.
My character is still alive after 20 something years and if I feel like logging in I'm sure there will be friendly faces who remember me.