Monkey Puncher is a game where your goal is to train a monkey to fight in boxing matches to save your kidnapped sibling. You can choose to play as either a boy or a girl character; the one you don't 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. These activities help improve his speed, power, strength, stamina, knowledge, and skills over time.
In all of these activities 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 let him go out and buy what he likes. This is a good way of obtaining certain items that are otherwise unobtainable.
Sparring involves pitting your own monkey against a computer-controlled one in order to raise every stat by a small amount. Dating your monkeys can also be an effective way of obtaining higher-stat monkeys, depending on which monkeys you breed and with whom.
During boxing matches, you don't 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. The match is won by either a count or by knocking out the opponent, with the winner being the monkey left with the most health at the end of the match.
Monkey Puncher was released for the GameBoy Color in December 2000 and is classified as a strategy game.