From the Introduction: Sanctuary introduces two to five players to the world of Unhallowed Metropolis in a single game session. This fully-detailed scenario includes five pre-generated player characters and statistics for non-player character creatures and is a suitable scenario from which to begin a long campaign. All you will need is a copy of Unhallowed Metropolis, some ten-sided dice, paper, pens or pencils, and a desire to commit all manner of atrocity on your players' characters.