Any feature (ACS?), for monsters that pursue the spot the player was last seen?

I haven't looked at many new source port features in a couple years, but that ZCajun thread got me wondering,

Has anyone attempted to allow monster AI to follow the place they last saw a player, or heard their gunfire? A hacky way to do this maybe with ACS/decorate, would be to drop invisible actors at the spots a player is seen by a monster (specific to each individual monster maybe?) and these "markers" are refreshed while a monster can see the player. The monster follows and shoots at you, but when it can't see you, it takes a default straight path to the last player position marked by the actor. If the player shoots their gun within earshot, the monster has a new point to travel to, until the player is seen or shoots again.

Other sounds a player makes (maybe with a smaller radius), include the grunting when using walls, or switches, and lifts.

Would these things be more feasable in-engine, or is there any scripting method a modder may have tried along those lines? I also think it may be fun to vary the player-seeking features the monster uses based on how smart/skilled it is (imp or baron), or its hearing ability (maybe Zombiemen have degraded hearing sense, relying more on line-of-sight), and if a troop of imps can communicate, maybe they coordinate their target area based on which imp has seen the player most recently.

And while the monster patrols the last known spot, if they don't see or hear the player for some seconds, more dangerous monsters might have a chance at following the player normally, simulating their ability to guess your moves, and some monsters might stay in the area, or go back towards their original location in the map.

Two words.
Brutal Doom.

There's even a youtube video showing Sgt mark IV testing the stealth mechanisms and the enemies were wondering around the area Doomguy was last seen.

Voros said:

Two words.
Brutal Doom.

There's even a youtube video showing Sgt mark IV testing the stealth mechanisms and the enemies were wondering around the area Doomguy was last seen.

Yeah although there is no ACS feature provided, but sgt.mark has created a damn fine stealth system for Doom. In fact, if you remove the "rescue marine" feature and return them to the invisible sphere pickup then the stealth feature really shines (this is for v20). I believe I saw that video where the zombiemen walked around the last seen location, tilting their heads around and after a couple moments return back to standing state.

Chezza said:

Yeah although there is no ACS feature provided, but sgt.mark has created a damn fine stealth system for Doom. In fact, if you remove the "rescue marine" feature and return them to the invisible sphere pickup then the stealth feature really shines (this is for v20). I believe I saw that video where the zombiemen walked around the last seen location, tilting their heads around and after a couple moments return back to standing state.

you are correct. Same for Imps.

It's actually possible if you modify each actor's behavior (for the monsters), ZDoom only of course .

3DGE is also capable of such a thing as well, using DDF and RTS. In RTS you can even do hacks to make them true node-followers so it ensures they go back to the node points after a certain amount of time or action chance. Lots of possibilities and ways of doing it.