Demon's Souls is set in Boletaria, a kingdom consumed by a dark being called the Old One following its release through the use of forbidden Soul Arts. Players take on the role of a hero brought to Boletaria to kill its fallen king Allant and pacify the Old One. Gameplay has players navigating five different worlds from a hub called the Nexus, with a heavy emphasis on challenging combat and mechanics surrounding player death and respawning. Online multiplayer allows both player cooperation and world invasions featuring player versus player combat.