Null sheen.
One thing to say about MUSHes and their ilk is that while you tend to have more roleplaying in them (actual roleplaying, as opposed with the 'roleplaying' you see on a RP server on WoW), things tend to be divided into 'scenes', much like you'd see in a stage play. Proper etiquette is to type everything in the third person and past tense, and to use a more passive mode of action when dealing with the environment (especially when dealing with other PCs and NPCs run by someone who is running an 'event').
These would be incorrect ways to do things:
I stab the man with my sword.
Mirikon grabs the stone and leaps out the window.
Mirikon swept Nadja into an embrace, kissing her deeply.
These would be correct ways to do things:
Mirikon thrust out with his blade, trying to stab the man in the chest.
Grabbing the stone, Mirikon turned, and dashed for the window, attempting to leap through it.
Mirikon stepped in close, and, if she did not resist, swept Nadja into an embrace, kissing her deeply.
The wording may seem a bit convoluted at times, but it is there because the MUSH environment is best described as 'collaborative storytelling', and so you don't want to step on people's toes. Also, it gives others in the scene a chance to react to what you wrote.
This brings up another point (one that applies well to play-by-post games like here on the forums, as well). The more you write, the more other players have to play off of, which makes the scene more interesting for everyone involved. If your IC (in character) post is a single sentence, what hook does that give the people you're with to play off of? Let's just take one of the examples above.
Crap:
Mirikon stabbed at him with his sword again.
Better:
Darting in, Mirikon slashed out with his sword, aiming for the guard's belly.
Best:
Flourishing his blade, Mirikon parried the guard's blow, using the motion to slip inside the man's guard. With a deft thrust, he stabbed upward with his blade, looking to impale the man upon his sword.
The first sentence conveys action, but gives absolutely nothing to the roleplay. The second is better, but is clearly not as informative as the third. In a text based medium, the more descriptive you can be, the better. At the very least, try for a simple paragraph (4-5 sentences) in a post.