One comes round the wall on your left, another on your right, and they shout orders to each other.

Jeff Orkin of Monolith told GDC in 2006 why it works: "we had only one A.I. programmer, but there are lots of A.I. characters." In their earlier games every behavior was wired by hand into state machines that grew "overly complex, bloated, unmanageable". One out-of-shape policeman who had to stop and catch his breath needed his own branch in the chase.

So in F.E.A.R. (2005) each soldier gets goals and a few actions and plans for himself. The rule that matters here: "always try to stay covered, never leave cover unless threatened and other cover is available". Each one keeps "an up to date list of potentially valid cover positions nearby", and when you expose his spot, he moves to another that still hides him.

There is no flanking in it at all: "The truth is, we actually did not have any complex squad behaviors at all in F.E.A.R." When a wall stands in the way, he "may take a back route and resurface on the player's side. It appears that the A.I. is flanking, but in fact this is just a side effect of moving to the only available valid cover he is aware of." Two soldiers moving up to cover on either side of you look like "some kind of coordinated pincher attack". The talking is decided "after the fact", and when the last soldier of a squad calls for reinforcements, "We did not really implement any mechanism for the A.I. to bring in reinforcements." As Orkin put it, "it's all smoke and mirrors."

The office, soldiers, cover markers and routes in this film are our own simplified version, built in code: one rule (go to the nearest cover you know that still hides you and nobody else holds), paths around the walls, slow motion in the game's spirit.

Which enemy have you given too much credit?

Sources: Jeff Orkin (Monolith Productions), "Three States and a Plan: The A.I. of F.E.A.R.", Game Developers Conference 2006 (the paper, from his own page).
Sounds and music: our own, made in code.
Unofficial. Not affiliated with or endorsed by Monolith Productions or Warner Bros.