I might have been the last person on Earth, born before 1980, to beat Super Mario Bros.
I remember playing RoboCop a long time ago on the CoCo 3, and beating the game using the least amount of ammunition possible, that game was a too easy. The bad guy at the end, you just shot one bullet immediately, and you kill him... if you pause, he opens up with machine gun fire and you die. I had never beaten a game the same day I had received it, before or since.