It is based upon Quest for Mordor by Brett Vickers, which was first written in 1988. It PennMUSH - PennMUSH is a mush server which keeps its database in the computer's memory. This makes PennMUSH suitable for computers which have plenty of memory or little disk space. For those of you who are new to moo-ing, a moo is a server for a virtual world, a computer program which users can log into and explore. You can walk around, chat with other people, and even create your very own rooms, and items.
Advanced users can extend perlmoo online by coding new commands in perl.
The MUD Resource Collection is a list of links to many useful sources of MUD information.