ZZAZZ Glitch. An unusual anomaly in first-generation games.

The ZZAZZ Glitch is one of the most intriguing and potentially dangerous programming anomalies discovered in the first generation of Pokémon games. This bug, which can completely transform gameplay and lead to loss of progress, has fascinated researchers and enthusiasts for years. In this article, we will take a detailed look at how this phenomenon works, its causes, and the consequences it can cause.

Origin of the Name

The name “ZZAZZ” comes from the effect the bug has on the player’s name. When the anomaly is triggered, most of the letters in the Trainer’s name are replaced with the letter “Z,” except for every third character. In the original case that led to the discovery and naming of this bug, a player using the name “OLD MAN” saw his name changed to “ZZAZZ” after the anomaly occurred.

How it works

This occurs when the player encounters a specific erroneous Trainer, which can be triggered using a technique known as the “Ditto Trick.” Depending on the game version, different combinations of Special Stats can trigger this bug:

• In Pokémon Red and Blue: Special Stats with values ​​of 248, 251, 252, 254, or 255, with the opponent’s Attack level unchanged (default 7).
• In Pokémon Yellow: the values ​​249, 250, and 253 also apply.

The technical reason for this bug is fascinating from a programming perspective. When a player encounters a Trainer, the game performs calculations to determine the amount of money they will receive upon winning the battle. In the first-generation games, money is stored in binary-coded decimal (BCD) format, which requires special arithmetic operations.

During these calculations, the game attempts to ensure that the value of the money does not exceed 9999. However, for erroneous Trainers with invalid money values, the arithmetic functions do not work as expected. This causes the memory pointer to be corrupted, writing the value 0x99 (153 in decimal) to the first two of every three bytes of memory whenever the calculated reward would exceed 9999 after the first time.

For Trainers triggering the ZZAZZ Glitch, this happens over two hundred times, destroying many key game variables.

Effects during Combat

When a player encounters a Trainer triggering the glitch, they will typically see their opponent send a creature marked ‘M (FF)’ or ‘Q ◣’ at level 153 into combat, with an unusually long health bar. Attempting to use a move or even preview their team will cause the game to crash (unless the player has exactly two or five creatures in their team).

Interestingly, you can easily escape from combat using any item (as long as it doesn’t display your party, like a Poké Ball). Using an item automatically ends the combat, which is also a result of data corruption.

Post-Battle Effects

After the battle with the Trainer who triggered the Glitch is over, the player will notice a number of drastic changes:

1. Team Transformation: Every creature in the player’s team, except those in positions multiple of 3 (third and sixth), will be transformed into a Bulbasaur at level 153. The first, second, and fourth moves of each Bulbasaur will be changed to Explosion.
2. Name Change: The player’s name will be changed so that every letter except every third letter is replaced with the letter Z.
3. Obedience Issue: Although the player’s name has been changed, the OT (Original Trainer) values ​​of the creatures in the team remain unchanged. This causes them to be treated as creatures from a different Trainer. Combined with the fact that most of them are level 153, they will always be disobedient (as even the Earth Badge is not programmed to ensure obedience from creatures above level 100).
4. Issues with subsequent fights: If the player attempts to fight a normal trainer after activating it, it will transform into a bugged trainer with the player’s avatar. Its name will be either the player’s original name, a name changed by ZZAZZ, or sometimes another incorrect name. Its team will consist primarily of a few ‘M (FF) or Q ◣. Attempting to fight this trainer will not immediately crash the game, but attempting to preview the player’s team will still do so. Using items will not end this fight. The trainer is nearly impossible to defeat, as the player’s creatures will not obey (and/or knock themselves out with the Explosion move), and at least one of the trainer’s creatures at level 153 has an unusually high amount of health.

Long-Term Consequences

The ZZAZZ glitch can have serious consequences for saved games:

• Save Loss: If the player saves after this anomaly occurs, the save file may be deleted if the trailing byte (0x50) is not present at or before the eleventh character of the player’s name.
• Dialog Set Corruption: This can corrupt the dialog set used for things like saving the game. To save the game, the player must reset the dialog set ID to its normal value. This can be done by talking to the nurse in the Center and canceling the conversation.
• Poison Effect: If the player changes the creature’s final variable to Bulbasaur at level 153 with the move Explosion, a poison effect may occur, decreasing unbound memory addresses by one for every four steps the player takes.

Various uses of this glitch in Pokémon:

There’s also a variant of ZZAZZ known as “Jacred,” which is triggered by using the Ditto Trick with a Special stat of 200 and using the Growl move once or twice. Since this is a variant of ZZAZZ, it’s possible to escape from the battle using any type of Poké Ball, though this is somewhat difficult because the backpack will be damaged and almost entirely filled with items called “PokéTrainers.”

After escaping, the player will find themselves in a sort of Glitch City. The game cannot be saved directly through the menu, as opening a team will freeze the game. The city doesn’t have a computer to save the game indirectly, nor does the Hub, where the save option in the menu can be restored by healing the player’s team.

Using the ZZAZZ Glitch

Despite its potentially destructive effects, some advanced players utilize it for various purposes:

• Pokémon Party Box Data Shift Glitch: This technique allows for data shifting between creature data and a specific point (ideally, an item terminator). This allows for manipulation of “post-20” bytes of items, which are actually unrelated data, allowing for things like teleporting to the Hall of Fame.
• Experimenting with the Game’s Limits: They utilize it to better understand how the game engine works and its limitations.

Glitch Summary

The ZZAZZ Glitch is a fascinating example of how even a seemingly minor bug in game code can lead to a cascade of unexpected effects. This anomaly, which takes its name from the distinctive Z pattern in the player’s name, can completely transform gameplay, changing the player’s team, their name, and how the game interprets data.

While it’s something to be avoided by most gamers, for bug researchers and enthusiasts, it’s a fascinating subject of study, demonstrating the complexity and fragility of computer systems. Whether you’re a casual gamer or a dedicated bug researcher, it remains one of the most intriguing phenomena in video game history.