Somewhere in the galaxy, there is a planet named Sera. It is protected by a wall of energy which its inhabitants call "Force". The Force is sustained by magical crystals known as seeds. When demons begin to invade the planet, the task of the nameless hero is to gather the seeds, which are scattered all over Sera's surface, to restore the Force of the planet, and to save it from demonic invasion. The entire exploration in Emerald Densetsu is done from a side-scrolling perspective, but it is not an action game, it is a solo turn-based RPG. Enemies appear randomly, their pictures super-imposed on the exploration screen (thus turning the battles into first-person view). The fighting is performed by selecting menu commands. The hero has "force points" and uses various "force techniques", which work like magic spells (healing, offensive, etc.). Defeated enemies give the hero experience points, allowing him to level up and become stronger. There is no money in the game, items, weapons, and armor can only be found by exploring the world, or dropped by enemies.