Gotta bump this. I finally started playing the game on my pretty low-end rig (P4 2.3 Ghz single core, 512 MB RAM, Geforce 6200), and it's definitely worth the $40 I spent for it. I have to run it in a window due to a glitch with the 6200 that causes artifacting in the sky, but otherwise, it's a top notch game. Now, note that I'm playing with the patch, which fixed a lot of complaints people had. The AI is pretty astounding - I've had instances where I'll be fighting one or two guys, then another guy will sneak up from behind while his buddy's distracting me, and pop me in the rear. And when I say sneak, I mean it - the AI actually will move silently to get around behind you, and wait until they're just near you before opening fire. Other times, if you fire at an enemy from behind an obstacle, then sneak away without them seeing you, the first place they'll look is where they last saw you. Other times, however, the AI can be pretty brain dead - clustering in groups and pointing their guns at the sky. These instances are more often the exception than the rule, however, and it doesn't detract from gameplay at all.
One memorable moment (creepiest video game moment ever, I've been telling everyone), is I had just gotten into a fierce gunfight with a gang of bandits. It should be noted that gunfights in this game are very alive and intense - you sprint from cover to cover, trying to pull a bead on your target, while bullet strikes kick up dust and debris all around you. The AI will actually act as a group and outflank you, while you have to run to counter that. Anyway, I put several of them down, and with the aid of my fellow stalkers, managed to win the day. I went off to go exploring (got a nice artifact!), and came back about twenty minutes later. Not only were the dead bodies still there, but lo and behold, I find that one of the game's creatures is EATING one of the people I had just killed! I stop and stare at it for a few minutes, not believing my eyes (even took out my binoculars to check that it was really doing it - it was). These creatures I've come to realize as being hostile, so I didn't approach it too closely. I tried to go around it to get to the door, but as soon as I did, another bandit saw me and opened fire. I retreated to cover, and turned only to see that the creature that had just been feasting, had heard the gunshots and bolted from the area! So now I was pinned down inside of a large walled compound - the enemy knew I was near the front, so I darted across the gate opening to the other wall, and tried to find another way out. Reaching a hole, I jumped out of it and landed on the opposite side. Bolting out to the side, I ran all the way out around the field and into a large ditch with some construction machinery. I crouch-walked through the ditch and went all the way around the back of the bandits, then proceeded to launch a surprise attack on their flanks. I managed to kill all of them after another invigorating gun battle, and progressed onto the next level.
If THAT'S not immersion, I dunno what is.
