I'm late with this, but that's the way it goes sometimes. It's a propluristemic rule inspired by Rafael Chandler's Narcosa project, for no specific game system. I've been reading Underworld Lore.
The edge of one or more Narcosmic spaces may bubble or whirl beneath the surface of reality wherever an imaginary world is being explored, awaiting indraughts of credibility...
If during a game the result of any roll causes at least half the players present to cry out in disbelief, one or more Narcosmoses are sucked up and begin bleeding in: each future roll is taken on a die one size above the current, e.g. use of a d6 becomes that of a d8.
If any roll thereafter produces a result not covered by the system, e.g. a roll of 1d8 on a damage table numbered only 1-6 comes up with a 7 or an 8, the players together decide how the Narcosmic actually manifests, agreeing a corresponding degree of psychedelic.
If agreeing's a little tricky, there's a robust procedure for this kind of thing in isophasmic.
Rafael says there's a pdf coming for all the material that arrived in time, but if you have an idea, why not post it anyway, for the pleasure of creation, possible second pdf or not._