My suggestion would be to try out Unity 3D - it uses a language similar to Java (C#), allows you to explore the basic AI stuff you seem to be interested in, and with their tutorials you can see the results of your work fairly quickly and you build actual projects from the ground(ish) up. And above all its fun, even if you're not an artist, or you don't come out with a polished game. If you're using windows you get the benefit of an awesome IDE (Visual Studio), but if not you can still get by pretty well, and Jetbrains is set to release a good cross-platform IDE for C# in the near future.