A quick anecdote from Stalker, which I've been replaying on and off, just to see what I can change/break.
I was playing through one of the early sections where an NPC character arranges to set up an ambush with you to rescue his captured colleague. The ambush was set, but things went batshit – completely different from the smoothly executed sequence of events I'd seen the first time I'd played through this section. For some reason the game spawned a hostile bandit patrol just within aggression range of my NPC partner. They shot at him at the exact moment the scripted ambush was supposed to occur. To deal with this random occurrence the game made the chap we were supposed to rescue vanish entirely, and then filled the other NPC with a murderous rage. He moved into the nearby building complex, with me still in tow, and systematically hunting down and killing every single bandit in the area.
Only when we reached the roof and the last bandit lay dead did the NPC stop and complete his designated plot device. He turned to his now non-existent companion and said “No problem, but you have this Stalker to thank.” Then he just stood there, frozen and unable to continue his existence thanks to the earlier interruption. When I returned an hour later he was dead.
Stalker is much more stable than its cousin, Boiling Point, which is in some ways a shame, because the sheer incoherent madness than Boiling Point produced was a kind of comedy you can't get elsewhere. Games that are so broken that they become surrealist nightmares are some of my favourite experience, and I'd hate it if that element of weird reality-breaking were completely ironed out of gaming.
Stalker: ultra-bleak survival shooter and unintentional slapstick death-comedy.