Do be aware that TinyMUSH includes no combat out-of-the-box. If you want to add any, you'll be writing it from scratch (or downloading some system someone else wrote, but I don't know of many of those at all). It won't be very efficient at all, either, so nothing large-scale...but it is kind of a fun exercise if you like the system. Still, it's scripting, not really a solid language. Also you'll be writing a lot of stuff like &cmd-find me=$+find *:@pemit me=[name(%0)] is in [name(loc(%0))]. Though when you think about it I guess that's not so bad for simple things.
(After BASIC, my next programming language was TinyMUSH code!)
If you want a social space, or if you want non-automated combat for roleplaying, MUSH is a great system and yes the ease of building is awesome. I've seen reproductions of the old ZORK games in it, and it wouldn't be hard at all to do that yourself. Many World of Darkness RPGs are built in TinyMUSH: Download and install some character sheet utilities (for setting up + viewing characters), and write a die roller (trivial), and poof you're ready to go.
MUCK has a language that's similar to MUSH, but it also has a FORTH clone that's an actual language and pretty efficient and powerful and even compiles in-game, but is still FORTH and thus
awfulfun. I'd say that in some ways, it is more well-developed than MUSH, but it also has no combat out of the box. Unlike MUSH though, I have seen successful automated combat systems built in MUCK! On the other hand, MUCK has become associated with a...certain audience...which you will probably notice if you search on it a little.
Having trouble trying to connect via SSH. How do you connect to the server on your own computer?
Address: 127.0.0.1 or localhost. Port: 6666. Leastways, that's what it was for me.
If 6666 doesn't work, give 4201 a try. And yeah, telnet, not ssh.