If memory serves me well, it was Mega Man 2. I was too scared to play (for some reason, just the possibility of losing would make me run away, screaming in terror), so I just sit next to my sister, watching her play it. When I finally grew the guts to pick up the controller, I remember playing that game night and day, writing down passwords to come back to it after school. I've lost count of how many times I've played Crash Man's level just to hear its soundtrack, it's just so catchy.