How do I prevent an NPC from wandering far away from its start location?
From OHRRPGCE-Wiki
You may have noticed that NPCs tend to wander rather far away from their starting location, especially if the map is loaded for a rather long time.
It may cause a problem if the NPC is important and the player can't find it because the NPC is not where it was supposed to be, or gets stuck in a narrow passage, blocking the player.
A common way to fix this is to place walls of invisible NPCs at points you don't want the NPC to pass, or in a box around the NPC. See How do I make a wall that NPCs can't pass, but Heros can?
A far more daring (and difficult) possibility would be to write your own random wander script for certain NPCs.
