Basic Information
Green Rocks is a speculative fiction trope. A green rock is an item or substance with wide-ranging and inconsistent powers. Essentially, a green rock has whatever magical or quasi-scientific properties the plot needs it to at the moment. In one session, it's a source of limitless power, in the next it opens a portal to the past, the session after that it's a super weapon, it frequently causes horrible mutations, the local conman applies it to turn water into wine, and if the plot ever goes way off the rails the GM will swing it in as a Deus Ex Machina or hand wave to tidy things up. Green rocks do anything, but only when the plot needs them to. Try as you might, you just can't predict what Green Rocks are gonna do.
In that way, Green Rocks are the opposite of Functional Magic, Magic A is Magic A, and Minovsky Particle.
In general, green rocks are a raw material of some kind and thus a form of applied phlebotinum - if they are a manufactured item, they're likely to drift more into artifact of doom territory.
Green Rocks have a lot in common with Wild Magic and Green Lantern Ring.
The term is derived from the common depiction of kryptonite.
Sources
Game and Story Use
- Over-reliance on green rocks will erode willing suspension of disbelief. Think carefully about when, how, and if to us them.
- Green Rocks are thus best suited for one-shots, and convention games, where the players don't have time to figure out how everything works anyway.
- Green rocks can also work in very cinematic campaigns where the supernatural is meant to be poorly understood and the rule of cool trumps everything else.
- Funny games usually handle Green Rocks just fine. If you want the players focused on goofy hijinks instead of plot and realism, green rocks will serve you well.
- The problems with green rocks are most pronounced in games where the PCs are professional wizards, research scientists, or detectives. In order to play this sort of character, you probably need to have a reasonable guess at how the supernatural elements in your setting works. If everything is hand-wavy and random, trying to play these sorts of characters can get annoying, fast.
- This is where definitions like Warpstone being soldified chaos come in useful - you can't quantify it because it's inherently unpredictable. Of course that also means you can't use it safely…
- One way to use Green Rocks is to allow the user to define their properties, within certain limits. This might be Doylist (spend a narrative editing point to define that the item can do this) or Watsonian (the substance reacts to will and belief, so it has the properties you think it has or want it to have).