Yep, specifically it was the radiant AI IIRC. They made a big deal of their work on this radiant AI system that was supposed to be like procedural AI behaviour and routines but they couldnt get it working and had to cut it.
It was actually a funny story they told about it. Essentially it wasnt that they didnt get it working but that it was incredibly chaotic and unpredictable. The example they gave was a shopkeeper who among other stuff was scheduled to sweep his shop every morning before opening, and to do this he needed a broom. Only he did not have one, so the radiant AI system told him he needed to go find one. Pretty innocent enough until he went next door and bludgeoned his neighbour to death in order to obtain their broom, before going back to sweep. Apparantly this was a huge problem that lead to a cascade of NPC on NPC murder that would leave your game world empty, so it had to be cut.
You could actually see this kind of situation happen in skyrim (which actually had some of this radiant AI system) with the dawnguard expansion, where there was a random event in which a mysterious stranger (read: vampire) would spawn randomly upon travelling to a town. The behaviour of this stranger was to walk around the town looking ominous and every night it would sneak into a random house and kill an npc to feed on them. Sounds fun right? Well no, because if you choose to ignore this NPC or didnt even notice them they would still go ahead and kill an NPC every night even when you were not there due to the background simulation. This lead to people playing dozens of hours blisfully unaware that entire towns were having their population fed upon before the player would discover that a bunch of the settlements were completely empty, much too late to revert to an older save.
Ive never really blamed the devs for cutting back on this as the consequences are far reaching and the complexity is pretty huge. But even the complexity they have makes these games truly something, and its part of the reason i love them so much. Where in other games NPCs and towns are merely an empty facade only meant to revolve around giving the player quests, BGS games are much more alive.
To hear theyre going even further with the background simulation in this makes me extremely excited about this game.
