I've been cursing the "Hard" AI in Catan for days now -- they never want to trade their wool for my brick, they always have the longest wall, and they're constantly putting the robber on my best tiles. They play the board like they've known it for years -- almost like they designed it themselves:

The creator of the board game, Klaus Teuber, helped to develop the AI in Catan. How invaluable was his input, and what can players expect from the AI?
About the time I was ready to start writing the Catan AI, we heard that Klaus Teuber had made "some Excel tables" on that subject. That sounded interesting so we asked to see them, and it turned out it wasn't just a spreadsheet it was a vast workbook of many different interrelated formulae, showing a lot of profound thought about the game system and ways it could be adapted to a really competitive AI. It gave us a huge Head Start in developing the AI - not only did we not have to "reinvent the wheel," we were able to concentrate on extending and refining the ideas Klaus had laid down and increasing their sophistication using tricks I'd learned writing AI over the years for games like Civ 2. So it was absolutely invaluable, and one of the funny things was apparently I was the first developer who was willing to take a serious look at Klaus' AI workbook and try to structure an implantation around that instead of "going my own way".