MUD Clients for Dark Castle
There a quite a number of MUD clients available for use, some are freeware and some are shareware.
The official MUD client of DC is Zuggsoft's zMUD as Zugg himself got
his start MUDding
on DC back in 1993.
It is a shareware client full of powerful scripting capabilities for the advanced MUDder.
Zugg also has CMUD available, another mud client which works in Windows Vista.
zMUD: Info | Download | Buy
CMUD: Info | Download | Buy
has a good list of available mud clients, should you decide to try others.