Aaahh!! Real Monsters is a platform arcade style video game released in 1995 for the Sega Mega Drive/Genesis and SNES based on the American Cartoon cartoon series of the same name on Nickelodeon.
The player takes control of Ickis, Oblina, or Krumm in their attempt to pass the Monster Midterm Exam at Monster Academy. 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. 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.
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 he can hurl at enemies. Collecting garbage sacks gives a limited amount of stronger ammo, fish bones. Collecting "monster manuals" will allow to perform a "scare" defeating any enemies on screen, or taking a certain amount of hit points off a boss.
Each monster's scare is unique and based on their favourite scare tactics from the series: Oblina pulls large amounts of garbage from her stomach and tongue and Ickis grows tall and evil. 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.
Source: Wikipedia, "Aaahh!!! Real Monsters," available under the CC-BY-SA License.