PerlMUD
PerlMUD is a MultiUser Dimension (MUD), a text-based environment that allows multiple users to converse, explore, and interact. PerlMUD is written in Perl 5.0 and is highly compatible with the well-known TinyMUD command set, which provides a friendly interface to your online environment. PerlMUD is inexpensive shareware, and complete Perl source code is included. Administrators can easily extend the PerlMUD system by writing additional Perl code.