“ A society or country has a unique method of correction. Criminals are imprisoned in a dungeon with two options: Serve their time, or try to escape. Those who manage to escape alive, their crimes are forgiven early.”
“ The players encounter an organization dedicated to toppling tyrannous governments; both good and evil. Secretly, they are led by the twin daughters of Lucifer / The Lightbringer / (Generic Adversary God). These daughters have an appropriate set of divine or demonic powers, but strictly speaking, are not evil.”
“ If you want to add a 'supernatural' touch to your campaign, define the rules of magic and the universe. Make your players comfortable with those rules. Then your new supernatural creatures must then break those rules.”