Most MU*s have an engine-specific DSL for the admin team/terraformers/etc. to create new rooms and items without having to program in C or C++, you'd just have to expose those controls to the players at large. Of course, most of those commands aren't intended to be used for playing on their own but for creating a playable environment.
It sounds like it'd be really fun if you could figure out a way to propagate those changes to the main server and then back to all the players in a way that avoids merging conflicts between player's frequent and potentially competing changes. On top of that, you could add a daily/nightly partial reset, which rolls back most changes except for the most used. That allows players to keep items and locations they use frequently and naturally control power-abusers who create instant death rooms and superweapons to dominate the server for the day.