I'm trying to make mobs that disappear or move (Or appear to), but only to certain players. (For storyline, mostly) Right now, I tried using images and controlling who saw what images, but I had problems: When I made the mobs disappear, players could still 'see' them if they moused over them, and they could still use verbs connected to them as if they were still there.
When I made the mobs move, I had similar problems. (To move them, I created an image)
For the mouse problem, it seems to me it shouldn't happen, if one uses the default mouse_opacity for those mobs, and they truly have no icon representing them (for the players that aren't supposed to see them, at least).
For the rest, read here (and use the forum search for more info, if needed): [link]
Unfortunately, complete player-experience-individuality is normally impossible. Some things can only be done dodgily, and some just can't be done. Implementing this with images also prevents you from utilizing some of DM's other features.