Remember that dream you had? The weird one where you spoke fluent Japanese to avian flu zombies who were also your freshman orientation guides? Now multiply that weirdness by the number of other people in your group. Getting on the same imaginary page is hard work for your average group of gamers. Unless you happen to be psychic, you’re not going to imagine exactly the same sort of fantasy world as the other guys at the table. I referenced this difficulty way back in Pit Trap, but today I’d like to throw a new wrinkle into the discussion. Depending on what system you’re playing in, the rules of the game get to dictate whose imagination is right and whose is wrong.

Here’s the example that got me thinking about this. In D&D 5e, the grapple rules say that “the target of your grapple must be no more than one size large than you.” In Pathfinder, there are several combat maneuvers that include similar “no more than one size category larger than you” language. You can’t push, trip, or overrun very large creatures. However, that language is conspicuously absent from Pathfinder’s grapple rules. That means you can’t push a dragon into a pit, but you are allowed to suplex Smaug to your hear’s content. (If that’s hard to conceptualize, then you haven’t read the legend of Los Tiburon.)

In terms of genre and content, these are very similar games. They’ve got the same heroes, monsters, epic quests, and magic items. They are forking branches of the same Gygaxian tree. Yet this very basic thing is explicitly allowed in one and disallowed in another. Whether or not you think it makes sense for Thursh the barbarian to wrestle an elephant depends on your individual conception of fantasy. However, whether or not you’re technically correct depends on the system, not the setting.

The easy solution is to say “leave it to the GM’s discretion.” From a designer’s standpoint, however, I’m less sure. Do you make it policy to avoid “you can’t do the thing” type rules, or is that a necessary part of a sensible system?