What Is RNG? A Lesson for Gamers


Have you ever felt overwhelmed by the number of acronyms in the world of gaming? From genres to technical terms, there’s a lot to keep track of. For example, what is RNG?

In this article we explain what RNG is in the context of video games. We’ll look at the meaning of RNG, study some examples, and see how it can even apply to speedrunning.

What Is RNG?

RNG stands for random number generator. This is defined as a device or algorithm that comes up with numbers by random chance. In gaming terms, then, RNG refers to events that are not the same every time you play.

While it sounds simple, computers actually have trouble generating random numbers. This is because computers are designed to follow instructions, which is the opposite of randomness. You can’t just tell a machine to “come up with a random number,” because giving instructions on how to choose something randomly is an oxymoron.

True RNG and Pseudo-RNG

Because of this, to truly generate a random number with a computer, you must use a physical device known as a hardware random number generator. This uses minute physical processes, such as electronic noise, to come up with random numbers.

As there’s no way for a person to predict or know what’s happening with these imperceptible events, they’re as truly random as possible. This type of RNG is vital in security-centric systems and thus appears in common forms of encryption. If someone was able to figure out how the system came up with “random” numbers for an encryption protocol, that would be a big problem.

However, this isn’t a concern with gaming RNG. For greater speed and easier reproduction, many programs, including games, use what’s known as pseudorandom number generation.

Pseudo-RNG uses an algorithm (think of it like a formula) that performs mathematical operations on a seed (starting) value to come up with a random number. To achieve different outputs each time, it’s important to use a seed that’s as random as possible.

A simple example would take the current number of milliseconds as a seed, then perform some operations on it, like this:

int rand = (a * milliseconds + b) % c

This is not truly random, because using the same seed will produce the same result each time. But it’s good enough for video games.

Examples of RNG in Gaming

Now that you know the technicalities of RNG, let’s take a look at some examples of RNG in games to see how it plays a part.

Loot RNG

RNG plays a big role in loot-focused games like Destiny, Borderlands, and Diablo. When you open a treasure chest or defeat an enemy, the reward it drops is not the same in every instance. The game determines it randomly each time, so you might end up lucky and get a super-rare item right away, or a low-level piece of armor over and over.

Of course, to keep the game balanced, loot drops are not completely random. They have systems in place to prevent you from getting the best weapon in the game from the first treasure chest you open. Each game has different ways of handling this, perhaps by limiting the equipment you receive based on your player level.

The drive to keep getting better loot is just one of the reasons video games are so addicting.

Determining Chance Percentages With RNG

Pokemon Critical Hit

Many games use RNG to figure out the percentage of a certain event happening. This is commonly seen in role-playing games (RPGs).

For example, when you attack in JRPGs like Persona 5 or Chrono Trigger, you may trigger a critical hit that does extra damage. This happens at random, though in many games you can increase your chance by using certain items. In a Pokémon game, RNG determines how often battles with wild Pokémon happen and which creatures you encounter.

Similar examples of this appear in games like Super Smash Bros. The character Mr. Game & Watch has a move called Judge that displays a number from one to nine when used. The value is determined with RNG each time you use it, with the exception that you can’t get the same number twice in a row.

Procedural Generation Through RNG

RNG is at the center of procedural generation, a popular trend in gaming. Procedural generation refers to the process of creating game content through an algorithm instead of crafting everything by hand.

Well-known games build around procedural generation include Minecraft and Spelunky. These games create unique worlds through a seed value, meaning every player gets a different experience each time they play through the game.

Like other forms of RNG, game developers add restrictions so that worlds aren’t generated completely at random. For instance, you won’t find random floating ground blocks above an ocean in Minecraft.

RNG in Speedrunning

There’s a chance you might have heard about video game RNG in the context of speedrunning. Since speedrunners aim to complete a game as fast as they can, they practice a lot in order to learn the game inside and out. Understandably, then, RNG adds an element of unpredictability to speedruns.

While it often causes issues, RNG isn’t always negative in speedruns. Having some variance between runs can make the game more appealing because it’s easier to improve your time with a bit of good luck.

Minor to Moderate Speedrun RNG

Sometimes, RNG is largely inconsequential to a run. The exact placement of where enemies spawn in a room, or whether you get a critical hit in a regular battle, won’t have a huge effect on your total time.

Other instances of RNG can cause more significant slowdowns. For example, in Super Mario Sunshine, the boss battle against King Boo involves spinning a slot machine with five possible outcomes. To damage him, you must first match three pineapple icons to spawn a variety of fruits.

After this, you have to throw a pepper at him to set his tongue on fire, followed by hitting him with any other fruit. With good RNG, the peppers will appear in a convenient location so you can quickly complete the fight. With poor luck, though, you might have to spin the roulette many times and burn some time.

Run-Breaking RNG

Some games have sections where getting unlucky with RNG can completely derail a run. One instance of this occurs in Banjo-Kazooie.

Near the end of the game, you enter a quiz show called Grunty’s Furnace Fun, which tests you with questions about your adventure. One type of square on the board asks you questions about Gruntilda, the game’s villain. If you talk to her sister Brentilda throughout the game, she’ll give you the answers to these questions.

However, the correct answers to these questions are random on every playthrough. Speedrunners don’t want to waste time talking to Brentilda, so they have to guess the answers at this point. This comes down to complete luck—if they pick the wrong answer too many times, they could die and lose a ton of time.

Having this RNG-dependent section at the end of the game is frustrating for a speedrun, because the runner can’t do much other than hope they get lucky. Despite this, speedrunners still often come up with ways to get around these roadblocks, as the video below shows.

RNG Manipulation

As we discussed, the pseudo-RNG of video games isn’t truly random, because you can reproduce results if you use the same seed. Many games use an internal timer as the seed, which can be fairly difficult to exploit. But other games are much easier to fiddle with.

Golden Sun, an RPG on the Game Boy Advance, is a great example of this. The game determines the rewards you get from completing a battle based on the actions you took during the encounter. This means that if you fight a battle against the same enemies using the exact same tactics, you’re guaranteed the same drops every time.

Speedrunners can use emulation tools to analyze a game and figure out if they can manipulate its RNG. They can then take advantage of it by guaranteeing a desired outcome or minimizing potential time wastes from RNG. But to the average player who doesn’t understand the seed, this kind of RNG is as good as random.

Now You Understand RNG’s Role in Gaming

We’ve looked at what RNG is, examples of how RNG affects games, and how it applies to speedruns. So you should now have a better understanding of RNG’s role in gaming. Now you should check out our favorite video game speedruns

7 Entertaining Speedruns Packed With Tips and Tricks

7 Entertaining Speedruns Packed With Tips and Tricks

Speedrunning lets you see incredible feats from experts. These speedruns will entertain and inspire you to become a better gamer.
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