-random treasure spawns. An author would place a piece of optional treasure, and set a percentage chance that it will appear or not.
I dont' think that this would be a good idea in terms of gameply. How should the user ever know that a loot exists if it only spawns randomly. I can't really see a benefit for this. Most likely the majority of the users will consider this a bug.
-optional path nodes (although I think this might already be possible with Dromed). The AI can choose to ignore a node or go on a different, separate path altogether.
I think this is possible with Dromed already. There are guard which have a pattern set out, and the (more or less) randomly choose which one they will follow. The path is still predetermined, but there are variations because the can select thenode they want to follow.
-AI actions similar to NOLF2. I never played the game myself, but I'd heard they do things that are unexpected, at unexpected times. Many times I've played Thief and thought to myself, "why is that cook just pacing back and forth?" Clearly for gameplay, NOT realism. "Why would a guy just be standing here in a dark room, facing the wall, then turn to the fireplace, back to the wall, back to fireplace, etc?" Again, gameplay, not realism. I'd heard that in NOLF2, AI will often kick a can around, or fidget (already in Thief), or even leave patrol to go to the restroom. That sounds like a fantastic addition that might really lend some tension to the overall experience.
That sounds like an interesting idea. I never played NOLF but it got a good ranking the games magazine that I read. I think this could look rather convincing if a guard search for a thief it knows must be there and then kicks a can in frustration because it can not find it.
-AI ladder climbing. Touchy subject, that, as it eliminates some safety and comfort in the game, but probably a good addition.
Doom 3 seems to support ladders so we are investigating this. Personaly I consider this a hot topic, because the AI in the Thief games was quite easily fooled with such things.