Punch Out (Nintendo, 1987) is one of only 2 games that sold over 2 million units by 1988 - the other one being The Legend of Zelda - making it one of Nintendo's best selling games of all time.
You're taking on the role of Little Mac, a 17-year-old boxer trying his luck against opponents like Glass Joe, Bald Bull, and King Hippo, plus - of course - the legendary Mike Tyson in the final fight. Mario being the referee was a cute little crossover-cameo.
Probably the best boxing game ever made? What made it so remarkable was its perfect balance of simplicity and depth: With just a few basic controls - left, right, punch, and dodge - the key was to have great reflexes and memorize the patterns of the opponent.