Kid Icarus: Of Myths and Monsters is an action platform video game for the Game Boy. It was developed by Nintendo and Tose and published by Nintendo, and is the sequel to Kid Icarus on the Nintendo Entertainment System. The game was released in North America on November 5, 1991, and in Europe on May 21, 1992. It was later re-released to the 3DS Virtual Console starting in Japan as an import on February 8, 2012, then in Europe on March 8, 2012, and then in North America on July 19, 2012. The story of Kid Icarus: Of Myths and Monsters is influenced by Greek mythology, and follows the angel soldier Pit on his quest for three sacred treasures. His objective is to defeat the demon Orcos, who has invaded the kingdom of Angel Land. The game features the core gameplay mechanics of its predecessor. Players explore two-dimensional environments while collecting items and fighting monsters. Kid Icarus: Of Myths and Monsters was named the 18th best Game Boy game by Nintendo Power, and critics commended it for its gameplay, graphics and music.

Kid Icarus: Of Myths and Monsters is an action platform game. It largely retains the gameplay of its predecessor, Kid Icarus for the Nintendo Entertainment System (NES). The player controls the young angel Pit, whose main weapon is a bow with an unlimited supply of arrows. The game's two-dimensional levels contain collectable items and obstacles such as enemies and traps. Pit's objective is to reach the end of three stages – the underworld tower, the overworld and the sky world tower – each of which is separated into three areas and a labyrinthine fortress. Upon completing one of a stage's areas, the player has the option of saving their progress, and Pit's health bar may be expanded if he has defeated enough enemies.

Unlike in Kid Icarus, the game's levels scroll freely in all four directions, which enables the player to explore previously visited environments. As an additional control feature, Pit can flap his wings in mid-air to slow his descent. In each area, there are hidden doors that lead to eight different types of chambers. In shops and black markets, the player may buy items such as healing potions in exchange for hearts, which are left behind by destroyed monsters. Information centers provide hints, hot springs restore Pit's health, and bat chambers give the player an opportunity to earn extra hearts. Treasuries hold items that can be obtained in a game of chance. In the sacred chamber, the god Zeus presents Pit with additional physical strength depending on the number of enemies defeated. The sacred training center has Pit take part in a test of endurance. His success will be awarded with one of three weapons, which will become active if his health is high enough: the protective crystals shield Pit from enemies, and the fire arrows and long bow increase the vertical and horizontal range of the arrows, respectively. During the course of the game, the player must find and defeat guardian monsters in the fortresses to retrieve three sacred treasures – the Wings of Pegasus, the Silver Armor and the Light Arrows. These are special items, which grant Pit new abilities in the final stage, the sky palace.