If you're talking about the character Mario, my first encounter with him was with the Atari 2600 port of Donkey Kong. I didn't know his name was Mario at the time and my first impression of the game was not great because it was pretty bad port. I love the Arcade original, but it was the Atari 2600 version that I played first. The first time I knew I was playing a Mario game was Mario Bros. which was a much better port on the 2600 and a fun game.
If you're talking about Super Mario Bros., my first experience was at a friend's house. We had pizza and I found out he had a Nintendo. I don't know why he didn't tell me, I guess his brother was the gamer in the family and not him. Anyway, I remember it clearly. It was like playing a cartoon. The graphics moved so smoothly and the screen scrolled for what seemed like forever. I was used to single screen games like on the Atari VCS so the NES seemed like a wonder machine and Super Mario Bros. was a revelation. I knew I had to have an NES, but it would be years before I'd have my own. The first time I played Super Mario Bros. is one of my most vivid gaming memories and it probably helped define my taste in games.
