Pokémon Crystal

About this build

Pokémon Crystal built from the pret/pokecrystal disassembly with rgbds 1.0.4, byte-identical to the v1.1 cartridge, running in the browser on a WebAssembly Game Boy Color core. You supply your own ROM: it is read in the tab, never uploaded, and the page recognises v1.0 or v1.1 by its SHA-1. Battery saves persist in this browser.

Built from

The real ROM, built byte-for-byte from the pret/pokecrystal disassembly, running on the libretro Gambatte core (EmulatorJS 4.2.3, WebAssembly)

Type

Decompilation

Game files

You supply your own Pokémon Crystal ROM (USA/Europe, 2,097,152 bytes). It is read in the browser and never uploaded. v1.1 sha1 f2f52230b536214ef7c9924f483392993e226cfb (the ROM this build reproduces), v1.0 sha1 f4cd194bdee0d04ca4eac29e09b8e4e9d818c133.

Code licence

EmulatorJS is GPL-3.0 and the Gambatte core is GPL-2.0; the pret/pokecrystal disassembly is unlicensed research. See web/THIRD_PARTY.md.

Assets

No game data is distributed. Everything comes from the ROM you load.

Source

andrewnakas/pokecrystal-web ↗

What has been tested

The v1.1 ROM builds byte-identical to the cartridge (sha1 match). In the browser, muted: new game to the player's bedroom, movement, an in-game SAVE, and the 32 KiB battery save restored in a fresh session showing the saved player. The published page was loaded through its own file picker to the title menu with the save store active and no off-origin requests.

Last tested 2026-10-08 in Edge (headless, muted). Full playthrough: not verified. How games are tested.

Known limitations

• Requires your own ROM; none is provided.
• Only the opening was play-tested: a new game to the bedroom, walking, and an in-game save read back in a fresh session. Nothing after that has been exercised.
• Audio is unverified: every test ran muted.
• Real-time-clock behaviour over days is untested.
• Link trading, battling and the mobile adapter features are not possible in a single browser tab.

Saves

Save in game the normal way (START → SAVE). The battery save is kept in this browser's storage and survives a reload. Clearing site data removes it.