In traditional computer games, it is not uncommon for the game world to be inhabited by numerous computer-generated characters, Non-Player Characters (NPCs). In pervasive games, players play among human non-players as well and it becomes very tempting to use them as a game asset; as non-playing characters. Humans behave unpredictably and intelligently, and for this reason games set in real social context become more challenging for players than any preprogrammed environment can be. But however tempting the idea is, the use of non-players has implications on people’s personal privacy. We report on a scenario-based study where people were interviewed about a set of game designs, all to some extent relying on information about non-players. We propose that in particular non-player anonymity and the ability to hold players accountable for their actions will affect non-player acceptance of pervasive games.