01 / COMPANION
Follower Pikachu
Travel with Pikachu close behind. Recent preview testing has concentrated on staying synchronized across Surf, battles and shore transitions.
Fan project · Game Boy Advance · Kanto adventure
Pokemon:
ThunderYellow
Version
2026 Special Edition. A fan-made companion to the FireRed and LeafGreen era, featuring your Pikachu follower and a growing collection of tested improvements and encounter events.
First Public Release · In DevelopmentThunderYellow has never had a public game release. Our first public release is being prepared and tested. When ready, the website will generate your complete .gba locally using your compatible, user-supplied LeafGreen Rev 1 game. No copyrighted Nintendo ROM is hosted here.
An electric return to Kanto
Built for the GBA and tested in Delta on iOS. Development focuses on a Pikachu that follows the player, classic region exploration, and fixes confirmed through actual gameplay sessions.
02 / DISCOVERY
Wild encounters and events
Expanded Gen III encounter testing includes different wild Pokémon, legendary encounters and event progression. Individual availability is still being verified.
03 / COMMUNITY
Help shape the release
Share findings, report reproducible bugs, and help distinguish verified behavior from features that still need testing.
First public release: in preparation
Your complete game, built on your device
When the first release is ready, choose your own LeafGreen USA Rev 1 game and generate a verified ThunderYellow .gba in your browser—without manual patching or uploading your ROM. Cover artwork is available today.
Current project status
Development testing has covered selected Surf-entry, shore-exit and battle transitions. These checks do not mean the game has been released or fully tested.
Verified areas
Selected follower recovery, Surf transitions and battle follow-up behavior have been exercised in Delta during internal development. No public ThunderYellow game release has been made.
Still being tested
End-to-end playthrough, remaining legendary access paths and compatibility still need verification before the first public release can be announced.
Play on iPhone or Android
One complete ThunderYellow .gba file will work in GBA emulators on either platform once the first release is ready. We recommend Delta on iPhone and Pizza Boy A Basic on Android. Need the compatible source ROM? Our guide explains how to find an authentic LeafGreen cartridge and create your own backup.
IPHONE & IPAD
Delta Game Emulator
Download Delta from Apple’s App Store and import your finished ThunderYellow game after release.
Delta App Store ↗ANDROID
Pizza Boy A Basic
Install this GBA emulator through Google Play and open the same ThunderYellow .gba on Android.
Android Google Play ↗About game ROMs
ROM use & legal disclaimer: Emulators may technically load ROM files obtained from different sources, but that does not mean every download is authorized. ThunderYellow does not provide, link to, or endorse unauthorized copies of commercial games. We recommend using a lawfully obtained original Game Boy Advance cartridge and making your own personal backup where permitted by applicable law. Rules vary by location; you are responsible for ensuring you have permission to use the game file you select.
Join the ThunderYellow community
Discuss features and announcements on Reddit. Have a reproducible problem? Use the GitHub tracker and include your exact build, emulator, and steps.