One of the things I look for in a roleplaying system is the “You Can’t Do That Here” failure point.

Obviously, there are things that a character logically shouldn’t be able to do. (Barring magical or technological aid, for example, a normal human being shouldn’t be able to flap their wings and fly like an eagle.) But that’s not what the You Can’t Do That Here glitch is about. You Can’t Do That Here happens when the structural or statistical quirks of a particular system make it impossible for a likely, probable, or desirable outcome to happen.

Imagine your favorite scene from a movie, book, or television sceries. Could that scene happen in your favorite roleplaying system? If not, why not? And can it be fixed?

These thoughts recently percolated to the surface for me during my read-thru and analysis of The Esoterrorists (which I also discussed here).

Scene 1: The detectives have a hit a dead-end in their investigation. Or perhaps their investigation has raised new questions. In any case, they return to the scene of the crime to look for new clues. Is there anything they might have overlooked? Is there evidence their later investigations suggest should exist that can now be found?

Scene 2: The teenage heroine is spending her summer vacation in the spooky, haunted house owned by her aunt and uncle. After spending seeral weeks in the house (enduring events of escalating strangeness), she passes down the hall and happens to notice for the first time a strange seam in the plaster. Investigating it more closely, she discovers a secret door and a staircase leading down to a hidden basement…

Scenes like these are a dime a dozen. They are also completely impossible if you’re playing The Esoterrorists: The system mandates that any clues which are to be found at a given location will be found by the PCs. That means you will never gain anything new by returning to a crime scene (unless new evidence has been deposited there since the last time you looked for some reason). Nor can you ever notice something that you previously overlooked.

And since this failure point in the system is a direct result of the system’s core design principle, there’s really no easy way to fix it: There’s an entire category of scenario that The Esoterrorists will never allow to be played out.

By contrast, these same scenarios can be absolutely trivial in other RPGs. For example, in the D20 system the former scene is modeled by either returning to the crime scene and Taking 20 for a more exhaustive search; or performing a new search with a circumstance bonus to model the additional insight gleaned from later investigations. And the second scene is nothing more than a series of failed Spot checks followed by a successful Spot check.

IN THE LENGTH OF A ROUND

On the other hand, I often see You Can’t Do That Here failure points being misdiagnosed by people who become trapped within the paradigms of the system. Perhaps the most notable example of this is the erroneous believe that, if it can’t be done in the length of a single round, then it can’t be done.

For example, in many discussions surrounding my essay “D&D: Calibrating Your Expectations” people would attempt to demonstrate the “ridiculous” number of feats which real world people require to be modeled “accurately” in the game system. A prime example was the Ride-By Attack feat:

When you are mounted and use the charge action, you may move and attack as if with a standard charge and then move again (continuing the straight line of the charge). Your total movement for the round can’t exceed double your mounted speed. You and your mount do not provoke an attack of opportunity from the opponent that you attack.

People would readily point to the example of any jousting tourney and say, “Anyone who jousts is capable of making an attack and then continuing to ride in a straight line.”

This is true. And, in fact, anyone in D20 can (a) ride up to someone; (b) hit them; and (c) continue riding past them. They just can’t do all of that in a single round.

This is about more than just defending the D20 system from an invalid critique, however. It’s about establishing a mindset in which you maximize the power and flexibility of your system of choice. Because the flip-side of You Can’t Do That Here is You Can Do That here, and that’s a lot more interesting.

Thinking back to the exercise we used to detect You Can’t Do That Here failure points, let’s turn it around now to a more positive use: Imagine your favorite scene from a movie, book, or television series. Can your system do that out of the box? If it can’t, what mechanics do you need to design to make it happen? And how can you design a scenario in which a scene like that becomes possible, plausible, or even probable? Can you generalize the case and figure out how to encourage scenes like that during a gaming session?

For example, imagine a scene where a kung-fu hero throws the bad guy through an aquarium full of piranhas. How can you enable and encourage that kind of scenery-interaction in your fight scenes? What mechanical structure can you use that will be (a) simple enough that the PCs won’t shy away from using it (as opposed to the default 3rd Edition grappling rules, for example); and (b) make the option as attractive (or more attractive) than simply hacking at the guy with their magic sword or throwing a punch at his jaw?

As a real world example, a couple of years ago I designed some simple counter-intelligence guidelines for the Gather Information skill. This took about 5 minutes. But having these guidelines made possible game content that would otherwise never have arisen: Previously “knowing that someone is asking questions about you” was a You Can’t Do That Here problem with the D20 system. Fortunately, it was a trivial one for me to solve — and now my PCs have to be cautious when asking questions about people; and occasionally they’ll be surprised to discover who has been asking questions about them.

Untested GUMSHOE – Mitigation Tests Trail of Cthulhu – System Cheat Sheet Untested GUMSHOE – Heat Exhaustion Track