I think NPC monsters should be both smarter and dumber when it comes to following players that have run away.
First of all, there needs to be a limit to the distance NPC\'s will follow a player. After this distance, they will stop following and return to their spawn point. In addition, If an NPC looses line of sight from you, they should only remember the last place they saw you, and go there. If when they get there they don\'t have line of sight, then they should stop following, because they shouldn\'t know where you are. In both cases, they should remember any players that attacked them or that they attacked or started chasing for a short while. They should then occasionally check to see if any of those players are within line of sight again, and begin chasing them again (closest one first, or by some WoW-like aggro level system) if they are.
The distance limit is important for one thing because in places like the open terrain npc monsters will chase players across the whole map, and then you end up with like ubernaughts in the forest path killing newbies (and even not-so-newbies for that matter). The line of sight stuff just makes them more realistic.
You could, if you wanted, create a waypoint system in all the maps and use advanced pathfinding, and in some cases make an exception to the line of sight rule if, for example, an npc chases you around a corner of the sewers and they lose sight of you, but there is only one place you could have gone. they could then chase down a little farther looking for you before giving up.
