KiraPatch

Disclaimer

KiraPatch is for educational and archival use.

Use it only with ROMs you legally own and dump yourself. Patch clean ROMs only.

What Is It?

KiraPatch is a patcher for Generation 3 Pokemon GBA games that raises shiny odds while keeping the game on its normal data-writing path.

Supported games:

• FireRed
• LeafGreen
• Ruby
• Sapphire
• Emerald

Supported clean USA/EU revisions are detected by CRC32 before patching. If the ROM is not a known clean match, patching is refused.

Who Is It For And Why?

KiraPatch is for players who want higher shiny odds across normal gameplay without turning shinies into fake visual-only results.

It is meant for people who want things like:

• shiny starters
• shiny wild encounters
• shiny static or gift encounters
• no Bad Eggs from broken writes
• no PKHeX legality errors caused by a visual-only threshold hack

How Does It Work?

The recommended modes are auto, canonical, and reroll.

In those modes, KiraPatch does not just change the shiny check threshold. Instead, it patches the Pokemon generation flow so the game keeps rerolling until it gets a real Gen 3 shiny result, then lets the game store that Pokemon through its normal path.

That means:

• it patches real shiny generation, not just visuals
• it keeps the normal SetMonData write path to avoid checksum corruption and Bad Eggs
• it validates the ROM before writing anything
• it always writes a new output ROM and does not overwrite the input ROM

Important note about high rates:

• 1/16 works, but it can cause noticeable pauses because canonical rerolls are expensive
• 1/128 or 1/256 are much smoother for normal play

Legacy modes:

• native and legacy are the older threshold-style patch modes
• they are not the recommended choice if legality matters

Are The Shinies Visual Or Not?

No. In auto or canonical, the shinies are real shinies, not visual-only shinies.

If the game shows the Pokemon as shiny, save editors like PKHeX should also see it as shiny.

Are They Legal?

Yes, that is the point of canonical mode.

In auto, canonical, or reroll, KiraPatch aims to keep the generated Pokemon legal by using canonical rerolls instead of a fake visual threshold patch. On supported ROMs, starters, wild encounters, and the tested static or gift paths are intended to remain PKHeX-legal.

If legality matters, use:

• auto
• canonical
• reroll

Do not use:

• native
• legacy

How Do I Patch The .rom?

Standalone Windows EXE

Build and run dist/KiraPatch.exe with build_standalone.bat, or use a prebuilt EXE if you have one.

The EXE is now the main user-facing launcher. It opens a compact GUI where you can:

• drag and drop one or more .gba ROMs into the window
• add ROMs manually with the file picker
• choose the shiny odds you want
• patch in auto mode

Recommended settings:

• odds=128 or odds=256 for smoother gameplay
• odds=16 if you want aggressive testing and do not mind freezes or pauses

Output naming from the EXE:

• <input_stem>.shiny_1inN.gba
• if that already exists, KiraPatch adds a version suffix automatically

CLI

python shiny_patcher.py "Pokemon Emerald.gba" --odds 256 --mode auto

Guided mode

python shiny_patcher.py --guided

If no ROM path is provided, guided mode starts automatically:

python shiny_patcher.py

Main arguments

• input_rom: source .gba ROM path
• --odds N: desired shiny rate as 1 in N
• --mode {auto,canonical,reroll,native,legacy}
• --output PATH: optional output ROM path
• --overwrite-output: allow replacing an existing output file
• --guided: interactive wizard
• --folder PATH: folder to scan in guided mode

Supported clean ROM CRC32 values

• 0xF0815EE7 - Pokemon Ruby Version (USA, Europe) Rev 0
• 0x61641576 - Pokemon Ruby Version (USA, Europe) Rev 1
• 0xAEAC73E6 - Pokemon Ruby Version (USA, Europe) Rev 2
• 0x554DEDC4 - Pokemon Sapphire Version (USA, Europe) Rev 0
• 0xBAFEDAE5 - Pokemon Sapphire Version (Europe) Rev 1
• 0x9CC4410E - Pokemon Sapphire Version (USA, Europe) Rev 2
• 0xDD88761C - Pokemon FireRed Version (USA) Rev 0
• 0x84EE4776 - Pokemon FireRed Version (USA, Europe) Rev 1
• 0xD69C96CC - Pokemon LeafGreen Version (USA) Rev 0
• 0xDAFFECEC - Pokemon LeafGreen Version (USA, Europe) Rev 1
• 0x1F1C08FB - Pokemon Emerald Version (USA, Europe) Rev 0

End

KiraPatch is built around one goal: higher shiny odds in Gen 3 without fake shinies, checksum corruption, or PKHeX legality problems.

Start with auto mode on a clean ROM, pick a sane odds value like 1/128 or 1/256, and patch a fresh copy.

License

Distributed under the MIT License. See LICENSE for more information.