Building robust logic for software programs is already a challenge in itself, and we've been doing that for over half a century. When it comes to building robust character behaviors, there are additional challenges in making the results believable and life-like. However, game developers have become more and more comfortable with the process over the past few years!

While animation and navigation technology has matured significantly over the years, combining the two together remains quite a challenge! Games like HEAVY RAIN include scenes with few pedestrians that must avoid each other (e.g. on a sidewalk), as well as huge groups that form the illusion of a crowd (e.g. in the station). What techniques are used to implement such situations, and how can the results be improved?

The single biggest challenge that AI programmers face is expressing behaviors... via animations. Character animation is at the same time the best tool for portraying intentions, but it's also the most expensive and time consuming process. As we strive towards better characters, animation is the primary battleground.

Successfully implementing a multi-threaded system for a game requires a good understanding of the theory. But there are also many "tricks of the trade" that experienced developers use in practice. This is particularly the case for AI since it interacts with many other sub-systems...