Programming with OpenGL
OpenGL, or Open Graphics Library, is a graphics library, aka API, that's free and open to the public's use. OpenGL is language independent, platform independent.
The API is defined as a number of functions which may be called by the client program, alongside a number of named integer constants (for example, the constant GL_TEXTURE_2D, which corresponds to the decimal number 3553).
I got into it when I first learned it in a computer graphics course I took, and wrote two board games by the end of the quarter: Slime War
Both of them have computer players which are super smart! I used a very simple AI algorithm to implement it - Alpha Beta Pruning. Google it and you'll see many websites explaining how it works.
I remember I had my computer player pit against human players and my computer player almost always wins! This is a very satisfying experience.