Mass Effect 3 is a science fiction action RPG set in space and on Earth. Gameplay focuses on exploration, combat, and dialogue. Players take the role of Commander Shepherd, a customizable commander of a spaceship, who must save the Earth from a large alien force called the Reapers. Players may affect the game world by importing save data from Mass Effect 2, which also determines which returning characters are still alive. Combat has been changed so that weapons are not restricted to certain character classes. Mass Effect 3 takes place shortly after the end of Mass Effect 2.