Wonder Boy in Monster Land, known by its original arcade release as Wonder Boy: Monster Land, is a platform video game developed by Westone Bit Entertainment and released by Sega in Japanese arcades in 1987 and for the Master System in 1988, with a number of other home computer and console ports following. The game is the sequel to the 1986 game Wonder Boy and takes place eleven years after the events in the previous game. After enjoying over a decade of peace on Wonder Land following the defeat of the evil King by Tom-Tom, later bestowed the title "Wonder Boy", a fire-breathing dragon called the MEKA dragon appeared; he and his minions conquered Wonder Land, turning it into "Monster Land". The people, helpless due to their lack of fighting skill, call for Wonder Boy, now a teenager, to destroy the monsters and defeat the MEKA dragon. Players control Wonder Boy through twelve linear levels as he makes his way through Monster Land to find and defeat the MEKA dragon. Players earn gold by defeating enemies and buy weapons, armor, footwear, magic, and other items to help along the way.

A platformer is a sub-genre of action video games in which the core objective is to move the player character between points in an environment. Platform games are characterized by levels with uneven terrain and suspended platforms of varying height that require jumping and climbing to traverse. Other acrobatic maneuvers may factor into the gameplay, such as swinging from vines or grappling hooks, jumping off walls, gliding through the air, or bouncing from springboards or trampolines.