Monkey Puncher is a game where the goal is to train a monkey to fight in boxing matches in order to save your kidnapped sibling. You can choose to play as either a boy or a girl character; the one you do not pick is your sibling.
Shortly after starting the game you are given your first monkey, Freddy. You can train him in skipping, using a punchbag, doing sit-ups, running and even going shopping. There is also a sixth activity, called sparring. These activities work to improve his speed, power, strength, stamina, knowledge and (for the latter activity) all of these, although only by a small amount.
In all of the aforementioned apart from shopping, you train your monkey by getting him to copy your actions; your actions are controlled by the rhythmic pressing of the A button. After a while, your monkey should be able to imitate your actions with ease, eventually being able to start the activity without prompting. In regards to shopping, you can send him out to buy what you want from a selection of items, or just let him go out and buy what he likes. This is a good way of obtaining certain items that are otherwise unobtainable. The rarity of items and the accuracy of which items it brings home from your shopping list increases as its knowledge does. Sparring involves pitting your own monkey against a computer controlled one in order to raise every stat by a small amount. Finally, you can 'date' your monkeys, either with each other, with a friend's monkey or in the dating shop available within the game. This is a good way of obtaining monkeys with higher stats, depending on which monkeys you breed and with whom.
During boxing matches, you do not have direct control over your monkey, but in between bouts you can do things such as refill its health, stamina, or both. You can also advise it on what strategy to use against its opponent. These matches are won by either a count or by KO'ing the opponent, however if time runs out before there is a clear winner, the winner is the monkey who is left with the most health at the end of the match.