Grum (and the other EL server devs) implemented the monsters invasions.
That is, an admin can use a special command and spawn monsters. Of course, there was a lot of role playing involved, with a story and all.
The players LOVED it, no one complained about anything :) Which is very rare.
Not only that they loved it, but they can't wait for more. And when you think that it was only a few lines of code (under 40)...

Meanwhile, I am working at BM, as usual. Almost finished the changes I wanted to do for the buildings, just a few more things left and they are done.
Now, some more details about the BM gameplay:
As with any other MMORPG, there will be various skills, that increase by practicing/using them. Unlike other MMORPGs, the skill level doesn't make any difference when you practice it, except for fighting and medicine.
So basically, someone with a lev 50 Construction skill won't build better than someone with level 5 COnstruction skill.
The difference, however, is that learning various technologies (such as, for example, new buildings) requires different skill levels.
Example (totally fictitious stuff):
Palace building (knowledge) requires a construction skill of 50, to learn. Someone with a skill under that will be unable to learn it, therfore they can't build palaces. But if two people, one with lev 50 and one with lev 100 both have that knowledge, they can build a palace without any difference based on their skill.