Three types of logic to employ in your RPGs

15 Jul, 2025

Three types of logic to employ in your RPGs

Over the weekend, I ran a Blades of the Inquisition oneshot with elements cannibalized from an earlier Warhammer 40K oneshot that I ran a few years ago.

My first stab at the scenario was a mystery module in which the PCs investigated a bunch of fancy rich people at a dinner party. In space. (That part is important.) The initial draft laid out all the connections between the various NPCs embroiled in an interstellar drug ring with exacting detail, alongside well-defined locations and a highly specific timeline of how the night would proceed if the PCs didn’t interfere.

The only aspects that survived from the earlier rendition of the scenario was the idea of investigating high-society space drug kingpins, a handful of NPCs, and certain elements of the setting. (Which, as I mentioned before, is space.)

I’ve been struggling to find a framework to convey the differences I see in the approaches I took to analogous material beyond the surface level stuff. (Stuff like, “Blades uses a d6 system and has flash backs. 40K rpgs tend to use d100 systems and also flashbacks aren’t explicitly a thing, but you can do the if the GM lets you, maybe, if she’s cool and nice. But don’t tell anyone, you don’t want to blow up her spot.”)

But I think what I finally landed on is a framework focused on the type of logic most important to the scenario — “logic” here not meaning rationality so much as the mindset the person running the game employs when evaluating cause and effect. So far, I’ve identified three strains of logic I see when I run and play games.

Real-world logic

Better known as “common sense,” this manifests as an understanding of how things in the real world operate applied to cause and effect in the fiction of the game.

“Dropping something heavy on the enemy down there will probably hurt him” is a simple example that is intuitive to anyone who’s ever tried to carry something heavy and dropped it on their toe, but it can be applied to more bizarre or unlikely scenarios.

I ran Lady Blackbird this weekend (a day before I ran the Blades game, for the curious). The game focuses on the eponymous Lady Blackbird and a scrappy crew of scoundrels trying to escape from a warship known as the Hand of Sorrow. The setting is sort of outer space, except it’s full of gas and ships use sonar and radio waves to communicate.

Near the end of the session, two of the PCs had blown a hole in the Hand by sabotaging a torpedo. The decompression sucked them into the void (don’t worry, they had EVA equipment that looked like old-timey diving suits), and the remaining PC had to figure out how to find them while in his space ship.

One option was to deploy the ship’s sonar system (again, space in Lady Blackbird has atmosphere), but my understanding is that being hit by sonar is somewhere in the “very fatal” range and I made it clear that would be a poor option.

The limits extend beyond natural laws — common sense reasoning around politics and human behavior can also be a very powerful way to make your world feel real.

Story logic

Also called “narrative logic” and associated with a “cinematic” style of play. Instead of trying to puzzle out what would actually happen in the real world, a GM or player operating off of story logic is focused on what would be the most dramatically satisfying thing to happen next.

Returning to Lady Blackbird, the titular character is trying to escape an arranged marriage so she can be with her lover, the pirate king Uriah Flint. It was a oneshot and I wanted Flint to make a dramatic appearance, so I foreshadowed him popping up at the end by having an NPC mention reports of heightened pirate activity in the region. Then at the end of the session, as the Hand of Sorrow vented atmosphere into space, his flagship rose up out of the fog and he announced himself over the radio.

If this was a TV show, there’d be a little “To be continued…” title card before a fade to black and rolling credits. Is Uriah showing himself in imperial space what a notorious outlaw would do logically? Maybe not. Dramatically? Duh! You can’t mention there being a sexy pirate captain and not at least give him a cameo at the end.

Dream logic

This style of thinking is concerned most heavily with symbolism and imagery. In this mode, things make sense as metaphors or allusions first and as actual events transpiring in the story second (if ever). Fairy tales, myths, and folktales operate on this kind of logic, and employing it provides a sense of surrealism or unreality to your games and scenarios.

I can’t think of an RPG that suggests operating entirely on dream logic throughout, but horror games tend to lean into more heavily than other sorts of games.

Over the weekend, I got to play in a session of Tremor's game Fiendgazer (run by the creator himself, no less!). The oneshot revolved around a group of people in a forgotten Rust Belt town dealing with a toxic cloud sickening their home, a miasma with roots that reached both literally and metaphorically into the town’s foundations.

The solution, of course, was to take an elevator into the cavern beneath the field at the center of town and blow up the town’s creepy pioneer founder who had been possessed by some sort of fungus monster. (We managed to escape by riding the elevator into a clearing tied to my character’s past. I rolled box cars twice in a row, which probably explains why things turned out as well as they did.)

Taking things to their logical extreme

There are clear parallels here to GNS theory, but I think one key difference is that these are not only modes of thinking the GM can switch between freely, but frameworks that can coexist and reinforce each other.

The typical framework for a Cthulhu Dark scenario is a metaphorical descent into madness typically accompanied by a literal descent from the mundane world on the surface to somewhere forgotten and decrepit, like an abandoned family crypt or a drowned city.

Along the way, the different styles of logic can help you decide what to do next (“You pushed the bathysphere past its limits as you tried to evade that squid, and the glass is starting to crack. What do you?”) and how to challenge or complicate things for your PCs (“Ok, you rolled a 1 — you find the map among the scavengers’ possessions, but you hear wet footsteps as he returns from his dive, what do you?”), but the experience is centered around a particular perspective that you can return to again and again.

A fun exercise is to apply the different types of logic we went over here to a moment in your game as you determine not just how the world reacts to the actions of the PCs, but the tone and tenor of the game.

Say A PC slays their NPC liegelord.

•From a common sense perspective, how will his heir react?

•From a story perspective, what should the next scene be?

•From a symbolic perspective, what’s the significance of the PC using an heirloom sword gifted them as a reward for swearing fealty to the NPC lying dead at their feet?