Limiting players in a room

[Dibalamin]

If there is a doorway you could also use a player.pl with the sub EVENT_CLICKDOOR.

Just have it increment a counter ++1 for each click with a quest::movepc and if counter > 6 it gives them a message saying the encounter is full? I haven't dove into global variables but you could have the counter tied to one of them and then use a sub EVENT_SLAY on the npc in the room to decrement the counter if he murders someone.

If no door I'd use the proximities & 2 different inaccessible areas of a zone....add a crate to a hall or something to block it off.