Probability-first simulation might be the future of simulation games
I recently saw a video where someone simulated an entire Minecraft world primarily through probability. Instead of literally running every creature’s movement and every tiny action in the background, the simulation determines what is likely to have happened based on the state of the world at any given timestep.
I realized that I already do the same thing in Pilgrimage.
(Which you can download here btw https://untrustedlife.com/pilgrimage/)
I’ve started thinking of this as a “probability-first simulation” or a “probabalistic simulation”: rather than coding every possible action as something that must physically occur step by step, you define the conditions and probability of an event, then allow individual stories to emerge from those rules. Each timestep runs the relevant probability checks to determine what happens within the world’s constraints. To simulate a golem moving, for example, I only need to know its current location, where it can move, and the probability of it leaving the rectangle representing its current location, just like in the video i linked above, that is essentially the basis of this concept, you know the constraints, the probabilities, and the chance of something happening each year. From that, you can determine whether it happened today, within the last hour, or at any point over any timestamp.
For example, imagine starvation has a 3% chance of affecting a historical figure each year. The game can convert that annual probability into the appropriate chance for however much time the current simulation step represents. It can then evaluate that chance for every important figure, regardless of whether the simulation is currently advancing by a day, a month, or several years.
The probability can be modified by the figure’s attributes, skills, environment, species, age, and current circumstances. If the starvation actually occurs, the figure can make defensive skill rolls to survive it. One creature might forage successfully, another might endure through sheer tenacity, and another might die.
Now apply that approach to combat, disease, reproduction, migration, political upheaval, territorial disputes, the construction of monuments, or somebody becoming a legendary historical figure. (Or MINECRAFT)
You can create incredibly atomized simulations where thousands of individuals have their own lives and histories without continuously simulating every footstep they take. You’re simulating the meaningful outcomes rather than every action leading to those outcomes. This is incredibly powerful.
Probabilisitic simulation itself obviously isn’t new. Simulations have used random rolls forever. What feels newer, or at least strangely underexplored, is treating probability as the actual foundation of a detailed world simulation rather than merely using it to add randomness to existing systems.
It also works beautifully with deferred generation in my experience. The game can leave something unresolved until it becomes relevant, then choose from the remaining possibilities based on everything the simulation has already established (As constraints). Once observed, that answer can become a permanent part of the world’s history.
The result is a world that can feel as though it has been running in absurd detail the entire time, even though much of that detail only needed to become concrete when it actually mattered and most of it was similified to nealry pure probability. Which is why its so fucking brilliant.
I really do think this is one of the keys to making more advanced simulation games. The answer to deep simulation is atcually to build systems that understand what could happen, how likely each possibility is, and deal with it when the simulation actually needs to choose an answer.
You don’t need to simulate everything. You need to simulate the possibility of everything, which is much, much less hard on a persons CPU. :3
Since that video now exists, im seriously considering making my own vidoe going through my own systems for a world simulation! Stay tuned! I just need to learn how to be good at editing videos.
Also they may have used AI to help make that sim btw….
I wasn’t going to mention that but the end screneshot of their screen made me sus as hell.
