Well I think mine was Super Mario World as well. I remember I got a 64 in 1 game with my gameboy classic when I was 5 or 6 or so. And Super Mario World was on it, along with games like Tetris and Pacman. Some other well known games were on it as well. The only downside was, none of the games had a save function, so I always had to start over from the beginning. That's why I never completed a game. But since I was so young, I didn't really care to start over everytime.
But nowadays I do not really play them anymore. I do still play old N64 games :)