Schrödinger and Chekhov
The centerpiece of Project Slaughterhouse is the zone stat block. It is coming in just a moment, but first, I want to take a brief diversion to offer the rationale for some of the odd decisions about how populations work in the Slaughterhouse. If you are willing to just take my method and accept it, you don’t have to read this and you can skip to the next page. However, if you concern yourself with realism in D&D and will get upset when I start telling you to just magically pull populations out of nowhere, read on.
Erwin Schrödinger was a physicist who helped develop quantum theory. Within the scientific community, he is probably most well known for his equation describing wave function in quantum systems, but that’s not important here (thankfully). Outside of the scientific community, he is most famous for his hatred of cats and love of necromancy.
In order to describe one of the more baffling bits of quantum theory, he proposed an experiment in which a cat was put into a box with a vial of poison and a radioactive element. The details are not important except to say that, during the experiment, there is an exactly 50% chance that the cat will turn out to be dead when you open the box. However, according to quantum physics, before the box is opened, the cat will exist in a weird in-between state of alive and dead. The universe (at least on certain scales) really does behave like this. Things can both happen and not happen until an experiment conclusively shows whether they did or not.
The whole point of the Schrödinger’s Cat experiment was to demonstrate that, in our universe, unless we make a direct observation, we can’t say what is really going on. And, if we make any number of indirect observations, we will find that the universe behaves as if everything is going on all at once. That’s a gross oversimplification, but its well enough for our purposes.
Meanwhile, a playwright named Anton Chekhov once famously remarked that “if you show a gun on stage in the first act of a play, that gun had better be fired by the third act.” Basically, he was saying that, if you include a detail in a story, it needs to become important in the story. Otherwise, don’t waste your time on it. If you spend two pages in a novel writing about a gun, the audience will feel cheated if the gun never comes up again. This has become known as “the Law of Conservation of Detail” or “Chekhov’s Gun.” Oh, and by the way, a red herring is a fair use of Chekhov’s Gun, but let’s try to stay focused.
In D&D, the problem is that, as much as we’d like to follow Checkhovs Gun, we don’t know (as DMs) what the party is going to do or what is going to happen in the story. So, in D&D, we use a modified rule called ‘Schrödinger’s Gun.’ Schrödinger’s Gun can be stated very simply: nothing in the game is true until the party observes it.
For example, suppose you have an important NPC in your dungeon. You know that they will play a vital role in an upcoming encounter. And you know the NPC can always be found in a certain place in the dungeon. You assume the party will meet the NPC so that they can be important later.
But, suppose the party keeps turning left when they should right and it appears that they are in danger of never meeting the NPC. So, you finally decide that the next unexplored room the party enters is the NPC’s room.
That’s Schrödinger’s Gun. Basically, the party has no idea what is behind any of the doors in the dungeon (or at any of the locations in your adventure or who is really trying to do what) until they open the door (or visit the location or discover the motive). Until that point, it could be anything. The players will never know what you had written down, they will only know what actually happened. If you change the identity of the villain, the location or use of an artifact, or the number of orcs in a dungeon, they will have no idea.
Another way which Schrödinger’s Gun comes up is when the party doesn’t have all the facts and takes action based on an incorrect interpretation of what they do know. For example, suppose the party discovers an artifact that can imprison elementals and primordials. They discover only that it ‘binds and contains elemental magic.’ You are hoping that they will pull it out and activate it later on when they encounter a primordial much later on. But, in the interim, the party encounters a genasi wild mage and is getting beaten up pretty badly. One of the players decides to whip out the artifact to take away his magic. You can say “no, you’re wrong, it doesn’t do that.” But, you might instead allow it to work somehow. Schrödinger’s Gun again.