Eeeeeh... I think it was Super Mario Land 2 : 6 golden coins. I played the hell out of other games too, but I preferred to play my favourite parts over and over again. This game, I just loved ALL of it, so I would beat it time after time after time. I think I would have beaten other games if saving was introduced sooner. I've never beaten Super Mario Bros 3, because I would play my favorite levels all the time, but if there was a save file I might have progressed further into exploring later levels.