You are Little Mac. You have entered a boxing match to prove you are the best. You'll be facing foes such as Glass Joe, King Hippo, and Mike Tyson himself. Each opponent has his own special attacks to contend with, and your up for quite a fight.
This game was something new to the video game world, as the first boxing game yet. This is notably the first, and probably only time, in which Mario starred in a game with a real person. This is also the first time Mario spoke. His first voiced word: "T.K.O." Another interesting note about this game was the recall of the original version. After Tyson went to jail, Nintendo wanted nothing to do with him. They recalled every copy of Mike Tyson's Punch-Out on the shelves. The later versions of the game were simply titled "Punch-Out!!" and Tyson was replaced with a different character of Nintendo's manufacture. Mike Tyson's Punch-Out was greatly mass-produced, so if you're looking for a copy of the original game, you probably won't have any trouble finding one.
An excellent boxing game, especially considering it was something new. The graphics were smoothe, clean, and don't get slowed down by fast action. The sound was not record-setting but fits the theme. Mostly the sound effects vary between the power of the punches you make. And of course Mario's voice. The gameplay was new and unusual, which is what made this game a hit. You go on fighting opponents, some of them tough, some of them not, in order to make it to the final challenge, Mike Tyson. Punching and blocking, punching and blocking your way to the top. Your rivals were often unpredictable (except perhaps for Glass Joe) and armed with strong special moves. Often times a unique strategy needs to be formed to beat the game.
Overall, this is unquestionably one of Nintendo's most classical, popular, and #1 boxing game to date. It is definetly worth a try.