Playing as Ickis, Oblina, or Krumm, the player explores various locales collecting specific items and scaring specific people the Gromble instructs the player to. The characters starts out in the sewer, and progresses through levels above in the human world. There are 25 levels and 5 bonus sections.
Players can switch between each character at will and each has their own special ability that often can be used to solve puzzles or overcome obstacles: Ickis can fly for a short time, Oblina can reach high ledges, and Krumm can scan off-screen areas. The monsters can also perform team moves, such as stacking on top of one another to reach items normally out of reach. The characters' main weapon is trash, which they can hurl at enemies. Collecting garbage sacks gives a limited ammount of stronger ammo, fish bones. Collecting "monster manuals" will allow them to perform a "scare" which defeats any enemies on screen, or takes a certain number of hit points off a boss’s health. Each monster's scare is unique and based on their favorite scare tactics from the series: Oblina pulls large amounts of garbage from her stomach and tongue, Ickis grows tall and more ominous, and Krumm makes a stink cloud. The goal of the game is to finish all levels and find all the items to pass the exam. Between each level, the Gromble appears next to a projector, showing the name of the next level. Some of the Gromble's actions can be controlled at this point. The game contained small samples of speech at some points, possibly taken from the series. The Gromble speaks at the projector, and the characters speak during their scare, and when hit.