Published on July 9th, 2012 | by Toast


The RNG: A Random Introduction

What am I reading?

If you’ve been lurking for any time at all, you’ve probably seen the acronym “RNG” floating around quite a bit. Despite its popularity, many people don’t really know what it is or how it works. A basic understanding of these things can be beneficial, especially in a Pokémon game.

Defining the RNG

So, what is this thing? RNG stands for Random Number Generator. The term itself is a bit of a misnomer for our uses but more on this later. Random Number Generators are used for just what the name suggests: generating random numbers.

Umm.. what?

Ok, time for a familiar example. Despite how the term may sound, RNGs are not traditionally some untouchable thing inside a computer. When you roll a standard die, you have an equal chance of getting each of the numbers between 1 and 6. Similarly, if you remember The Game of Life, you’ll recall there was a number wheel in the center, sometimes called a spinner. This wheel had an equal chance of ending up on any number between 1 and 10. Dice and spinners are both RNGs, and you’ve likely been using at least one of them for a long time in board games.

If Pokémon was a board game, we would roll dice or spin the wheel to determine when we encounter a wild Pokémon and what attacks would land. Pokémon is not a board game, though, and computers don’t roll dice.

Computers don’t roll dice

Of course not! Instead of rolling dice or using a spinner, computers rely on a completely different kind of RNG called a PseudoRandom Number Generator (PRNG). This is what your games use, and it is usually what people are talking about when you see “RNG” around here.

Don’t get hung up on big words here: “Pseudo” is just a Greek prefix meaning fake, or false. So, what we have here is something that is not really random. How is that possible? Well, computers just follow instructions, so they can’t really come up with a number out of thin air. Instead, they use a specially designed equation to make something that only appears to be random.

What’s the difference?

Generally speaking, the numbers created via PRNG appear random. There are, however, at least a couple of significant differences between numbers produced by PRNGs and something that is truly random.

At first glance, the numbers from a PRNG look random. On closer inspection though, there is a pattern. Given a few values created by a PRNG, you can come up with the original equation that the computer uses to create them. From there, you can predict exactly what it will be. This is the basis for RNG abuse.

Because of the kind of equation used in many PRNGs, the same number cannot be generated twice in a row. Generally, this effect is minimized through a few mathematical operations, but it is still there.

Why do we care?

So, why do we care? There are actually plenty of reasons. The PRNG impacts a lot of things in these games from wild encounters to what’s on TV. It also plays a role in damage done in battle and the added effects of attacks, among other things. To be able to compete, you need this thing to work with you.

Understanding the PRNG has brought a step up in competition. We’ve developed methods to take advantage of the PRNGs predictable nature. Using these methods, we can get Pokémon with a preferred nature, optimal stats and even add the aesthetic appeal of shininess. These methods are collectively known as RNG abuse.

The PRNG is the chaos behind the game and understanding it is the first step to controlling it.

About the Author

is a programmer and RNG researcher. He is the author of EonTimer and has contributed to RNG Reporter among other things.

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