I have to say the same thing. It was one of the most scary moments in video games coming up against these guys. I actually feared pretty much every encounter at least at first before I got used to them.

TBH I won't agree with anyones sentiments about AI in this thread. Most people wouldn't know good AI if it snuck up behind them and slapped them in the face with a 20 pound wet trout. Theres a reason why Bungie made the AI so vocal in Halo CE for example, if they didn't the players wouldn't get the fact that the AI was responding to them 95% of the time. These are the playtesters too whom professionally play more games than pretty much anyone else out there so no experience doesn't make you a good pick for good AI.

@Khuutra

Oh how they loved to do that. Their smoking out techniques when you hid for too long were superb. Once I had hidden behind a pillar out-shooting two of them, one throws a grenade to the side of the pillar, I run away from the pillar, and the other one headshots me xD

I loved that game, it was one of the most intese FPS experiences i've ever had.

halo should be taken out

i would say killzone 2

@Squilliam

Yeah, the first times through the game were a fearsome feat when it came to fighting those guys.
I guess everyone will have a different opinion about what they think it's the best AI they've played. Personally I think that the AI in Halo CE was good, not perfect as it had some flaws, but better than most games even by today standarts.

I don't know what makes AI particularly good: I only know how it functions in terms of my experience. Half-Life's Marine AI was the one that affected my experience the most, so I think it was the "best" AI in terms of how it factored into experience, even if it was not the most sophisticated from a programming perspective.

@Khuutra

Exactly, I think that the "best" AI that anyone has played is the one that has had the biggest impact in terms of gameplay and experience for them. Even old style FPS had an AI that could drive me insane sometimes, especially in games like Hexen, Heretic and Doom 2.

Cry some more.

http://aigamedev.com/open/reviews/halo-ai/

killzone 2

even on easy they are really smart

That's a tough sell to be honest. It depends on how you define good A.I.

It seems as though some of those dev tricks are meant to fool the player into thinking there's good A.I. , making the game challenging but in a fun way. They take advantage of the fact that most people can't distinguish good A.I. They also realize that complicated A.I. can fool and confuse players making the gaming experience less enjoyable. Bungie seem like great developers.