I’ve been wrestling with a peculiar thought experiment for a couple of years now, one that keeps surfacing in my mind like a persistent itch. It starts with a scenario that’s deliberately stark: imagine you’re alone in a prison cell with absolutely no variation in your environment. The lights never shut off, there’s no way to tell time, and you can’t see anything through the window except an identical empty cell across the way. You have a concrete slab for a bed, basic plumbing that can’t be manipulated for entertainment, and clothing that’s been thoroughly searched. The key constraint here is that there’s truly nothing variable about your situation—no loose buttons to throw, no interesting floor tiles to count, no external inputs whatsoever.

The Random Number Problem

In this environment, how do you generate a random number? It’s a question that sounds academic until you consider its implications. Sure, you could think of a word and count its letters, or try to come up with numbers “randomly” in your head, but these approaches introduce significant bias. Your brain has patterns, preferences, tendencies that make true randomness nearly impossible. If you’re stuck in that cell for months or years, rolling virtual sixes over and over again because of cognitive bias could seriously impact whatever mental game you’re trying to play.

This is where computer science offers an interesting solution, though adapted for human limitations. Most programmers are familiar with pseudo-random number generators—complex mathematical formulas that produce sequences of numbers that seem random and are distributed well enough for most purposes. But these typically require computational power beyond what your brain can manage.

Enter the multiply-with-carry method, invented by George Marsaglia. It’s one of the few algorithms I’ve found that you can actually execute mentally. Here’s how it works: start with a two-digit seed number, say 23. Take the ones digit (3) and multiply it by 6, giving you 18. Add the tens digit from your original seed (2) to get 20. Your random number is the ones digit: 0. Now 20 becomes your new seed, and you repeat the process.

The beauty of this system is its simplicity and reasonable distribution. It has a cycle of around 60 numbers before repeating, uses most numbers in that range, and the math is manageable even when you’re mentally fatigued. The downside? It’s obscure enough that I always forget the details and have to look it up again.

The Mental RPG Application

Why does any of this matter? The random number generator serves a specific purpose: enabling a solo role-playing game that exists entirely in your mind. Think of it as storytelling with unpredictable elements, where the random numbers influence plot developments you wouldn’t have chosen yourself. Instead of knowing exactly where your mental narrative will go, the randomness introduces genuine surprise and keeps the experience engaging.

This is where bias becomes genuinely problematic. If your “random” system consistently produces the same kinds of results, your mental game becomes predictable and loses its power as a psychological escape. A truly random element preserves the sense of discovery that makes role-playing games compelling.

The Tattoo Solution

Here’s where the concept gets interesting from a design perspective. What if you could encode everything you need for this system into a single tattoo? Not just the mathematical process, but a complete framework for interpreting the results in meaningful ways.

I’ve been envisioning something inspired by the alethiometer from Philip Pullman’s His Dark Materials series—that compass-like device with symbols around its circumference that provides cryptic answers to questions. The tattoo design would feature ten icons arranged in a circle, each corresponding to a digit from 0 to 9. When your random number generator produces a result, you’d look to the corresponding symbol for narrative inspiration.

Imagine the Sun icon assigned to 3—it could represent outdoors, heat, summer, light, goodness, or any number of interpretations depending on your story’s context. The Serpent might be 7, suggesting danger, wisdom, transformation, or deception. Each symbol becomes a storytelling prompt that your random number selects.

The design could incorporate the multiply-with-carry instructions in artistic elements—perhaps stylized mathematical notation woven into decorative borders, or the core formula embedded in a way that looks like ornamental text. The goal is creating something beautiful enough to be permanent body art while functional enough to serve as a complete game system.

Alternative Approaches and Refinements

I’ve also considered using Fibonacci sequences for randomness, though this would require pre-computing and encoding a longer sequence of numbers into the design. There’s potential for additional mechanics too—perhaps drawing imaginary lines across the tattoo to create intersections between symbols, generating more complex narrative prompts from the combinations.

The constraint that drives all of this is permanence and self-sufficiency. Whatever system gets encoded needs to work without external references, additional tools, or aids that could be taken away. It needs to live entirely on your person, accessible in any environment, no matter how restricted.

The Broader Appeal

While this thought experiment started with the extreme scenario of solitary confinement, the concept has broader applications. How often do we find ourselves in boring, unstimulating environments—long flights, waiting rooms, insomnia-driven nights—where a self-contained mental game system could be valuable? The tattoo becomes a permanent escape hatch, always available when your mind needs engagement.

There’s something appealing about having a complete game system that exists independently of technology, external objects, or other people. It’s gaming reduced to its essential elements: imagination guided by structured randomness, stories emerging from the intersection of conscious creativity and unpredictable mathematical sequences.

I’m still working out the details—which ten symbols would be most versatile, how to encode the mathematical instructions elegantly, what additional mechanics might enhance the system without overcomplicating it. But the core concept feels solid: a beautiful, functional tattoo that transforms any boring environment into a potential adventure, using nothing more than the random number generator living permanently on your skin.

The question isn’t whether you’d ever need such a thing, but whether the possibility of needing it justifies the preparation. In a world where we’re increasingly dependent on external tools and digital systems, there’s something profoundly appealing about carrying a complete game in your skin—a permanent reminder that entertainment, storytelling, and mental escape are always within reach.