Scorched Earth taught me the concept of software versions. It was the first program that I ever knowingly interacted with more than one point-release of. I had version 1.0, but a friend had version 1.2. My very young mind was boggled by the concept of software being updated.
I was thinking about this last night. "If it's a different... version.. then it's a different game"
I think Super Mario 2 being what it was really messed me up.