I am a huge MUD games fans. Though, MMORPG's rising popularity gives text-based games a strong opponents that they can't match.

I started my own MUD engine (codebase) a while ago and I'm now looking for various ideas or features you guys have encountered in various games.

I have come across various ideas so far :

1. A kind of GTA's wanted stars systems. Guards of different strenghts will comes for you.
2. The MUD game I'm familiar with do not have the abilities to attack someone in a room foreward. This could be fun when playing a ranged/spell caster class.

Please note that I'm looking ideas for a medieval/fantasy theme MUD.

What else ?

I am aware that there is no good answer for my question and I'm not allowed to post Community Wiki yet.