Now, some people / almost everyone might want to swear at me, because this would kind of take away the classic-ness of the games, because it would make some stuff too hard, etc... but I gotta give this idea.
It would be cool (IMO at least) if there was added a new option for modders, that is attaching a navigation file to their maps, or adding navigation files to already existing maps (aka making the story maps' monsters intelligent).
Basically that file would mainly consist of waypoints declared over different coordinates on the maps, which would link to other waypoints declared at most X units away, and could be linked through a forced link to other points further away or could be forced unlink from close points to indicate obstacles on the way, so let's say there is a waypoint right next to each other, but there are barrels on the way, so an unlink is forced so the monsters should go around that obstacle rather than try to go over it, realize they can't and start roaming around dumbly.
What monsters should do is associate themselves with one waypoint, and calculate what waypoint path they should take in order to reach the player (which would associate itself with another waypoint). Idle monsters would be left alone so as to not add unecessary processing, and the waypoint list should only be updated when the player changes waypoints (OK, this is probably something that you would think of if you actually implement this, but I like to say this kind of logic stuff because then I don't get lost in my idea and I can just scrap this over and delete all this post if I figure out this wouldn't work because I didn't think of X or Y, and because when I have some idea I like to kind of make a whole project on how it could work and stuff, that's just habit. Whatever, ignore me / ignore my attempts at giving ideas on how it should work if you don't like obvious information), and I think unless the player teleports, most paths could be recalculated based only on the monster's current point, the player's new point and the player's old point (so only the end of the list would be changed rather than the entire list), but this could give some problems for example on a circular room with a big obstacle like a pillar. Also, I think points could also be flagged with move to and shoot to, so monsters will try to move around barrels but will shoot over them, for example. OK, enough of my stupid obvious information xD
Now what I'm all about: making the monsters use waypoints so they are more intelligent at finding the player and makes the game more challenging.
Now, maybe the fun of those games is that the monsters sometimes get stuck behind objects and you can kill them, or they leave you alone after you run away from their room far enough. Maybe this would make the game just damn too hard. I mean, I just went through a level on episode 4 of Heretic where you face a Minotaur almost heads-on and if it wasn't for a bunch of barrels around the room he chased me to, I guess I wouldn't beat it. So I kind of got an idea to get around that: if such a feature was implemented, there could be added either an option on the menu or up to two difficulty levels (probably one based on the medium difficulty, but at least one based on the hardest difficulty, because theoretically it should be 'the ultimate challenge' or something like that), so people that want to play classic can play classic and people that want to play challenge can play challenge. I think this would be fun. What do you think?