The year is 2081. The Earth has become a devastated planet, overrun by monsters, controlled by a mysterious entity known as Increaser. The only hope to save the beloved Earth lies with you, a young warrior named Dan. You are sent in a time machine to the year 1999, when the monster invasion was beginning. Your task is to find your way through monster-infested labyrinths and to defeat the Increaser – whatever he (or it) is.

The game is an action platformer with more emphasis on exploration than on "jump & run" gameplay. You don't die immediately if a monster touches you, but have a life bar that gets gradually depleted as you are hit. Defeated enemies bring you energy points, which you can spend to buy upgrades. You start with a sword, but later obtain other weapons as well. The game's structure is not entirely linear; many areas have different doors leading to different places.