My hobby has always been, since I was about eight or nine, video games. Not just playing and enjoying them (formerly) in arcades and (currently) at home, but figuring out how they worked, the programming methods involved, system capabilities, and so on.
Coding games myself would have been a lot bigger in my hobby toolbox earlier, but for the fact that home computers pretty much sucked until about 1995, and I didn't get anything decent until 2001. I whiled away the previous fifteen years with an Apple II and then a 486.
Coding on old systems was a real hoot, though it's a rather slow way to learn how to code up to today's speed. All the younger whippersnappers who just got started will probably outpace me. (Note to self: Must finish hypnosis app that makes people dumber.)
Of the last four years, been coding in something called FreeBASIC, which is (IMHO) a lot more versatile than C++ and in many ways better.
Right now the race is on to see if I can finish my big huge epic RPG before the world comes to an end. Difficulty: There's two other projects in front of it.