Uncertainty game-mastering is named after the Heisenberg uncertainty principle, in which observing an event causes it to devolve onto one of the possible outcomes. Events or scenarios do not have a fixed form until the players take action.

Alternate terms: quantum physics game-mastering, player-driven scenario design


  • The GM has a scenario that involves a village being taken over by monsters. The GM does not decide on which village until the PCs announce they are traveling, at which point it becomes the next village they visit.
  • The players decide they want to visit a pawn broker. The GM decides there is a pawn broker and assigs the NPC an identity and relevant traits.
  • The PCs are pursuing a mystery. The GM waits for them to concoct a sensible explanation, then adopts it as having been true all along.


Uncertainty game-mastering has the advantages of reducing unnecessary prep time; avoiding genuine railroading, zorking, and other contrivances; and increasing the speed at which adventures unfold.


If done ham-fistedly, uncertainty game-mastering can be a more subtle but just as problematic form of railroading. It can remove meaningful choices. It also removes potential sources of inspiration, as the interaction of unforeseen variables can be a source of creativity.

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