I just played through the original FEAR again. The AI is still damn impressive and blows away the AI of most shooters to this day. The visuals did not age well at all, though, and the horror stuff just feels cliche these days. Still worth playing for some of the most enjoyable and difficult battles against AI opponents in a shooter.
Yeah, FEAR is fantastic. One of the best shooters ever made, precisely because of that AI. I also think people don't try to replicate that because they think lowly of people and don't want to challenge them with that sort of behavior.
I disagree. I think making AI that behaves in a manner that seems human is incredibly difficult. Probably the biggest feature about the AI in FEAR is its ability to retreat, regroup, and come at you from a different angle. Making AI that knows when to back off and how to use group tactics is just plain hard. And of note, the entirety of the level design was built with the abilities of the AI in mind. Put the same AI in a level that doesn't allow for as many tactical options and it wouldn't seem as smart. The AI here also worked well in part because of the slow-motion ability of the player. In a game like Call of Duty or Battlefield, the player would just get worked over and over because the AI would just be too difficult for a single person to overcome.
I do think, though, that Monolith just has some excellent AI programmers. After all the studio's most recent accomplishment in the nemesis system in Shadow of Mordor, and that utilizes many of the same tactical retreat systems used in FEAR. Whoever is doing that stuff for them is just really great at his job.