PerlMUD is a text-based environment that allows multiple users to converse and interact.
Complete Perl source code is included. Administrators can easily extend the PerlMUD system by writing additional code.
Version 2.1 lets the MUD administrator decide whether new users should be allowed to build. You control this by setting the $allowBuild flag in the configuration section at the top of the mud source file to 1 for yes or 0 for no.