Pseudorandom number generation

A pseudorandom number generator is an electronic device or software's attempt at creating a random number. Just as rolling a dice is not 'random' (being determined by factors such as force and angle of the throw, as well as friction), computers cannot be truly 'random'. In order to generate 'random' events in games and other forms of software, they must get as close to looking it as they can. There are limitless ways of accomplishing this. The degree of apparent randomness depends on the ability to predict the next result of the algorithm.

Mechanics

First, the generator must have a seed, a number to start with. This number is usually a date and time referring to the first time that the algorithm is called during the usage of the device or the software's active session. Seeds are also occasionally derived from user input, as it is highly improbable to do the exact same thing more than once, making it appear 'random'.

This number is put through a complex algorithm, and the result is formatted according to the needed context. The raw result then becomes the seed for any subsequent uses of the random generator. Therefore, the nature of the generator is a recursive algorithm.

In the Pokémon games

Let Seed be a number between 0 and 0xFFFFFFFF or the Result of a previous call to the equation.

Result = [(0x41C64E6D * Seed) + 0x6073]

This algorithm is used for the following:

• Encrypting Pokémon data in the save file.
• Generate the personality value of a wild encountered Pokémon.
• Generate the individual values of a wild encountered Pokémon.
• Determining the species of a wild Pokémon.
• Determining the Pokémon Lottery Corner lucky number.

Alternative pseudorandom number generator

The game also uses a different algorithm to alternate, reroll, or modify a previously randomly generated value. The algorithm works in the same nature; however, the equation changes to:

Result = [(0x6C078965 * Seed) + 0×1]

This algorithm is used for the following:

• Shiny Pokémon Ranger Manaphy egg restriction.
• Determining the species of a Pokémon swarm.
• Determining the Pokémon in the Great Marsh.
• Determining the Pokémon in the Trophy Garden.
• Mystery Gift shininess restriction for Type 1 Wonder Card Pokémon (currently all released with variable Natures).

RNG Abuse

RNG abuse, also referred to as RNG manipulation, is a procedure that manipulates the pseudorandom number generator in the main series games to obtain a desired Pokémon. It is commonly used to obtain Shiny Pokémon, Pokémon with high individual values, Pokémon with a specific set of individual values that yield a particular Hidden Power output (regarding Type and/or move Power), or Pokémon with certain Natures.

As the initial seed is predictable, the "random" numbers are predictable as well. Pokémon Emerald's initial seed is always 0. The Generation IV and V games use the Nintendo DS's date, time, and delay between starting the game and pressing "Continue" to generate the initial seed.

The random number generator is used to determine a Pokémon's personality value and individual values when it is encountered or received. After the initial seed is discovered, the player can control a Pokémon's characteristics with frame-precise timing. There are several methods used to create a Pokémon's characteristics — for instance, a bred Pokémon and a stationary wild Pokémon's characteristics are generated through different methods.

There are some limitations. As a player's Trainer ID and Secret ID numbers determine a Pokémon's shininess, Shiny Pokémon generated through certain methods can only have certain individual values. Also, it is not possible to manipulate the Nature of a Pokémon obtained through a Wonder Card.

In the Pokémon fandom, RNG abuse is slightly controversial. Proponents note that RNG abuse does not require a third-party device and that the Pokémon obtained through RNG abuse can be obtained through normal gameplay. In addition, Pokémon obtained through RNG abuse have been used at the Video Game Championships, an official tournament. However, some players believe that RNG abuse is cheating, as the action of picking a Pokémon's characteristics is similar to using a cheating device.

External links

• Pseudorandom number generator on Wikipedia
• Smogon's explanation and guide on Pokémon Emerald RNG Abuse
• Smogon's explanation and guide on Generation IV RNG Abuse
• Smogon's explanation and guide on Generation V RNG Abuse

This game mechanic article is part of Project Games, a Bulbapedia project that aims to write comprehensive articles on the Pokémon games.