I see a lot of people answering this question with stories from when they were kids. But my instincts were never to "fix" or "make" game. I was all about wanting to master the game as written. I wanted to know it and play it "correctly" so that I knew the outcome of was "legit".
I spent most of college deep in the Interactive Fiction community and wanting to make stuff for that.
I didn't start wanting to make (tabletop) games until a good number of years into participating at The Forge where the idea of games having unusual forms and tackling unusual subject matter was introduced to me. The very first game I ever finished was called Misunderstood. A game about awkward friendships and hurt feelings. It basically had a small prisoner's dilemma mechanism where if you got it right everyone was happy and became better friends. If you got it wrong then everyone's feelings were hurt. The game ended when the circle either formed healthy harmony or fell apart from too many misunderstandings.
It's all been down hill in subject matter from there!
My second game was Fight Sphere.... we really don't talk about Fight Sphere.
(I'm just going to keep triggering the IntroduceYourself bots with these posts, aren't I?)