I'll put my vote in for Buckland's Programming Game AI by Example. It is very approachable, code-heavy, and it's also got some great examples to visualize the

I'll put my vote in for Buckland's Programming Game AI by Example. It is very approachable, code-heavy, and it's also got some great examples to visualize the techniques discussed. Very easy to translate what you learn reading this book into any projects of your own, particularly if you take the time to actually code the examples and work through the exercises at the end of the chapter. I've got a copy of Ian Millington's AI book that I need to finish reading. So far it seems to be very good. It's not as example-driven, but it seems to have good breadth on real-world game AI topics. The Game Programming Gems series is worth reading through, if, as others have noted, a little dated in places. The general game design and AI sections hold up better than some of the high-performance math and graphics tweaks included from that era. I believe a good portion of them are available for free online, although I may be confusing one of the other Gems series.