Monster Business is influenced by vintage platformers such as Mr. Do and Dig Dug. Bob owns a zoo, but the creatures (monkeys, snakes and all the rest) have gone on the rampage and must be stopped.
Its levels contain ledges, ramps, and similar, and scroll vertically. Bob must aim his short range gun at them for long enough to cause them to explode, then release to send them up the screen, and ideally hit them again, to release as many bonus fruits as possible. This must all be done within a time limit – complete it before being told to hurry up and you get a time bonus.