The world is actually the playground of a secret higher god (the lesser gods being his servants). Where a series of Good races fight a series of Evil races (orcs, demons, etc.) to keep the ubergod entertained. Things like magic and Experience are constructs of the gods to keep a constant conflict, and the Choosen Heroes and Villains are just pawns to keep the balance. If one of the two factions achieves total victory and the world becomes peaceful the ubergod gets bored and resets (destroys) the system.