Avalon takes place in the future after the destruction of earth. A group of people known as the Avalon-cult flees to an distant planet called Avalon, which had an earth like climate. Unfortunately, one day their village was suddenly attacked by hundreds of strange creatures. The leader of the colonists, Lee, tried to negotiate with the monsters but was captured. A young man named Mace volunteers to seek for Lee and to find out what the monsters wanted in order to secure the safety of human life on the planet.
The game itself is a console style RPG seen from an top-down view, where you solve puzzles, fight monsters and talk to the villagers. The battles are, like in many console RPGs, strategic and are turn-based.