For me, it was the creative, puzzle-solving, game-like nature of it. Then I got my first job, and I had 100% autonomy, so a friend of mine and I got to solve real problems for real people in the real world. It was a rush. Making people’s lives better through software is still the biggest motivation for me.
(btw what ended up being the resolution of your great grandfather’s ring? I was flipping through your history to see what you work on :)
And the creative, puzzle solving, game like nature of it is now completely gone. Answering architectural questions isn't fun to me. I loved the process of writing code and now I hate being a software developer.