Well most of what i'd like doesn't have much to do with AI per-se but pathfinding. I mentioned spiders on vertical surfaces before, but jumping/climbing guards would be nice too. I find that RIIT (or whatever the acronym is) has increased belivability of actors very much, although it doesn't have much to do with AI. Generally people seem to think AI is about things that it's not, extending it to all actor actions instead of a planning component prioritizing goals for the death of the player AI in a game like thief is there to look cool and not fuck up. Planning is not really needed IMO. What are the guards going to plan about? About how to mow you down more efficiently with swordcuts or interception routes from multiple sides to prevent escape? There are not even open kill-zones in thief-likes since there are no repeating guns. Or grenades to throw around corners. The important parts like scheduling door transversal are already done in C++. What's really needed is a bit more imagination by the mappers. Have guards not immediatly engage in combat, but throw a switch to increase security throught the level, have them carry objectives to a 'saferoom' if you're detected, have a 'hitman level' where a time-limit is a factor going towards a objective, or where the objective itself moves; build a narrative beyond the basics. If some AI support is needed to support these types of levels, then explain what you'd like.