[This is a guest post by writer-designer Elizabeth Shoemaker Sampat of Two Scooters Press, who produced the much-admired indie tabletop RPGs Mist-Robed Gate, It's Complicated and more recently Blowback.]

I'm going to go out on a limb here and say that all games are simulations. Sure, they’re sexy simulations, where you can have adventures and do things terrible and wonderful that you would never do in real life. But the reason these games are so compelling is that they’re framed in a realistic way; though the actions or narratives may be wildly removed from what transpires in your day-to-day life, there’s enough comforting simulations framing the experience to give you a sense of something real.

In a physically-simulative game, there are lots of little things that give the player an immersive and organic experience playing; the environment, artwork, and sound all work together in order to create tone and texture. The big thing that frames the experience, though, is the physics engine— the algorithms that dictate the actions and reactions of the world to the people affecting it.

If you drop a ball in a game with a basic physics engine, it will hit the ground in the same amount of time, every time, and rest there. If you’re working with a more complex physics engine, the result will be affected by how hard you drop the ball, what the ball is made out of, what the floor is made out of, and the angle at which the ball hits the floor. Now, most people can’t do that kind of mathematics in their head to check the physics engine’s work, but as long as the reactions are satisfactory on a basic level, the surprise and causality will make the reaction feel natural, organic, and real.

As I understand it, physics engines are a real pain to code from the ground up. That’s one of the appeals of text-based games with scripted narratives. You don’t have to mess with that stuff! Is it cheaper? Probably. Easier? That depends. Essentially, you’re trading physical complexities for narrative complexities, and that means designing an engine that emulates narrative physics.

But Elizabeth! You say. Are we talking about simulating the experience of tabletop roleplaying— where your character can choose from an infinite number of actions, and then a real person chooses from an equally infinite number of reactions? Because we haven’t perfected artificial intelligence yet.

Not exactly.

In my last guest post, I talked a bit about an indie tabletop concept called Right To Dream, which is a distinct play style that some people see as an ideal. Of course, there’s more than one play style: Right to Dream is all about building a world to explore, discarding the parts that don’t fit your dream of how the world should be, and simply existing within that dream. The experience isn’t about changing anything; instead, it’s about learning what more is there, as opposed to changing the things you’ve already discovered.

Another play style concept is called Story Now. It’s a very popular one: forget the pages and pages of setting material you have to learn before you start to play! Just start in the middle of a story. Start telling it. Affect the narrative, change the world, build an incredible story with your character at the center of it all. This is the kind of game that is extremely difficult to port to a scripted-narrative digital game: in order to give the player the feeling that they can affect the world, the game’s narrative physics have to be incredibly robust. Just as all of the different variables in how you drop a ball can lead to wildly different outcomes in a sophisticated physical game, the number of inputs and outcomes for a narrative game would have to be equally complex.

There’s a fertile middle ground here; much in the way that many lapsed D&D players enjoy World of Warcraft because it scratches the same tactical/social itch, you can design a game that scratches the “Story Now” itch without being a slavish reproduction of that style of game.

In my next post, I’ll diagram a Story Now engine, and talk more about how to emulate that style of play.