I have similar memories with my dad and Donkey Kong Country. We'd play and advance through the game together, but he'd go back at night (after I was alseep) and replay levels to find the bonus areas, then show me the next time we played. To this day I can still remember certain ones that he showed me.
I'd love to find a game that me and my son can bond over in similar fashion someday. (He's still working on learning to crawl atm. Lol)