Wonder Boy in Monster World was developed by Westone and published by Sega, released for the Genesis in 1991 as the fifth entry in the Wonder Boy series and the first to fully commit to the action-RPG structure the later Monster World games would refine. Players control Shion, a young adventurer who can purchase and equip a growing arsenal of swords, armor, and shields from town shops, exploring interconnected areas and dungeons to save Monster World from the return of the dragon Mercator. Its blend of straightforward platforming combat with light RPG progression, buying better gear rather than leveling up through experience points, gave it a distinct pace from both pure platformers and traditional RPGs of its era. Well regarded on release and increasingly influential in retrospect, it is often cited by fans and later Wonder Boy revival developers as one of the series’ best entries and a key touchstone for the action-RPG genre’s evolution on consoles.