Interest in Artificial Intelligence
Background first, too: I am currently third-years student in Information and Computer Science at a Chinese university.

I think most of your problems can be solved by common algorithms. For example, Sudoku game, can be solved by searching, or DLX(Dancing links and X algorithm) if you wanna improve the performance. 

I think you can do some exercises to improve your basic skills. Some online judge services are suggested, such as Codeforces, SPOJ, poj.org, etc. There's an interesting game on a contest few days before. codeforces->contest->346->problem->A 

Some of AI algorithms are based on searching. To improve the performance, we have some optimizing skills such like evaluation function(e.g. A* algorithm) or randomization(e.g. GA or Simulated annealing). Another part is base on learning, responses of a quest are according to large amount of data(e.g. ANN, and some algorithms for classifying). 

Huge amount of code cannot be avoided. And some Lisp symbolic programming languages are good at such things. You can learn it if you're interested. 

So just enjoy playing with what you make!