The Mudlib provides Graal Kingdoms - and, by extension, Kingdoms Debug - with its extra Multi-User Dungeon options.
This library also extends GScript with a few extra commands that allow it to access and modify MUD accounts.
The Graal Kingdoms mudlib is derived from Crossfire.
With the recent advancements in GScript, some playerworlds are scripting their own MUD type system.
For scripting resources related to the Graal Kingdoms mudlib, see here.