Crystal

A native web port of Pokémon Crystal, translated from PRET's Game Boy disassembly. The game runs in TypeScript and reads graphics, maps, sprites and dialogue from the user's own ROM. No original game assets are included.

Current milestone: all of Johto, from the opening to Blackthorn City, the Rising Badge and the Battle Tower. Play in a minimal Crystal-style interface with Game, Savegames, Map, Pokédex, Link and Friends tabs. The native canvas fills the play area, and the live local map follows your position. The Map tab also shows the Johto map with your location, the towns you can fly to and the areas open so far. Save, export and import work now. The Pokédex tab shows the Pokémon you have seen and caught. Link and Friends show their planned scope without placeholder data.

Walk around your home, the town and its buildings at the original walking speed. Mom gives you the Pokégear and asks the day of the week. The teacher stops you from leaving town. Your rival shoves you away from the lab window. Professor Elm introduces his errand, and you choose Chikorita, Cyndaquil or Totodile. The Pokémon's picture and stats come from your ROM, and you can nickname it. Elm's aide then gives you a Potion. These scenes run the game's own event scripts and movement data, with native choices and naming.

With a Pokémon, head west along Route 29 to Cherrygrove City. Wild Pokémon appear in the grass and battle you with their original moves. The route has ledges, signs, an item ball and a Berry tree that regrows daily. Townspeople wander and look around as in the original. In Cherrygrove, the Guide Gent gives a tour, the Poké Mart buys and sells items, the Pokémon Center nurse heals your party, and a whiteout returns you to the last Pokémon Center you entered.

North of Cherrygrove, Route 30's trainers battle you. Bug Catcher Don spots you from a distance and walks over; Youngster Mikey battles when you talk to him. Each sends out two Pokémon, and beaten trainers remember you. The Berry house gives a Berry, and a Potion is hidden on the route.

Mr. Pokémon gives you the Mystery Egg, and Professor Oak gives you the Pokédex. Your rival challenges you in Cherrygrove on the way back, and Elm's aide gives you Poké Balls. Back on Route 29, the Dude shows you how to catch Pokémon. From then on, open PACK in a wild battle to throw a Poké Ball. Caught Pokémon join your party, and you can give them a nickname. In battle, PKMN switches Pokémon or opens a Pokémon's stats, and when one faints you choose the next. PACK's Items pocket uses healing items, revives, Ethers, X items and Poké Dolls.

Start opens the start menu. POKéMON shows your party: open a Pokémon's stats, change the order, rearrange its moves, or give and take held items. PACK shows your pockets: use Potions, status healers, revives, Ethers, PP Ups, vitamins, Rare Candy and evolution stones, give or toss items, and ride the Bicycle. Pokémon evolve when they level up after a won battle (press B during the flashes to stop it), and learn new moves outside battle too. Field moves work from the party menu too: Cut, Surf, Strength, Flash, Whirlpool, Waterfall, Sweet Scent, and Softboiled or Milk Drink to share HP. Fly opens the Fly map to choose a town you have visited, Teleport returns to the town of the last Pokémon Center you entered, and Dig or an Escape Rope leads out of a cave through the entrance you last used. In PACK, SEL registers a key item such as the Bicycle, and Select then uses it. POKéGEAR shows the clock, the Town Map card with a cursor over every landmark, and the phone: call Mom or Professor Elm. Call Mom after the catching lesson and she offers to save some of your trainer prize money. Once the Mystery Egg is delivered, talk to her at home to save or take money, or to switch Daylight Saving Time; with enough saved, she buys items and dolls for you and calls to say so. POKéDEX lists Pokémon in Johto order up to the last one you have seen. Open a seen Pokémon to read its number, category and footprint; once caught, its height, weight and two pages of text appear. Your name in the start menu opens the trainer card: your ID, money, Pokédex count and play time, then the Johto leaders with the badges you have earned. OPTION sets the battle style (SET skips the offer to switch when a trainer sends out the next Pokémon) and the menu account (the start menu's descriptions); text speed, battle scene, sound, print and frame are kept for later. Bill's PC can move Pokémon between the party and any box. The poster opens the Town Map.

The Pokémon Center PC opens Bill's PC, your own PC and, once you have the Pokédex, Professor Oak's rating. Deposit, withdraw and release Pokémon, and switch or name boxes. Store, withdraw or toss items. With six Pokémon in your party, a catch goes to the current box. When that box fills up, Bill calls you. The bedroom PC also lets you arrange owned decorations.

Route 31 leads to Violet City, Sprout Tower and Falkner's gym. South of Violet, Route 32, Union Cave and Route 33 lead to Azalea Town: follow Kurt into the Slowpoke Well to stop Team Rocket, beat Bugsy, then herd the Farfetch'd in Ilex Forest for HM01 Cut and reach Route 34. Kurt makes balls from apricorns overnight. In the Ruins of Alph, solve the chamber puzzles to unlock wild Unown, which appear in their letters and fill the Unown Dex.

In Goldenrod, get the Bicycle, challenge Whitney for the Plain Badge and answer the Radio Tower quiz for the radio card. Visit the department store and Underground shops, the Name Rater and haircut brothers, check the Lucky Number show, or exchange Game Corner coins for prizes. The Route 35 gate gives you Kenya with Randy's MAIL. In the Game Corner, play the slot machines and Card Flip for coins.

North of Goldenrod, Route 35 leads through the National Park to Route 36. On Tuesdays, Thursdays and Saturdays, enter the Bug-Catching Contest: catch the best bug you can with the Park Balls before time runs out, then wait for the judging and the prizes. Water the odd tree on Route 36 with the SquirtBottle from Goldenrod's flower shop, then follow Route 37 to Ecruteak City. Beat the five Kimono Girls in the Dance Theater for HM03 Surf. In the Burned Tower, your rival challenges you before the floor gives way and three legendary Pokémon flee; Raikou and Entei then roam Johto's routes, where you may meet them in the grass. Morty is then back in his gym for the Fog Badge.

West of Ecruteak, Routes 38 and 39 lead past the MooMoo farm, where seven Berries cure the sick Miltank, to Olivine City. Your rival is there ahead of you, and Jasmine is at the top of the Lighthouse with her sick Ampharos. The Café gives HM04 Strength and a fisherman gives the Good Rod. Surf Routes 40 and 41 to Cianwood City: Suicune flees across the water and Eusine challenges you, the pharmacy hands over the SecretPotion, and Chuck waits behind the boulders of his gym for the Storm Badge. His wife gives HM02 Fly. Mania lends you Shuckie, the Poké Seer reads where you met your Pokémon, and the photographer offers a photo, which needs a Game Boy Printer. Bring the medicine back to the Lighthouse, then challenge Jasmine for the Mineral Badge.

East of Ecruteak, Route 42 runs past Mt. Mortar to Mahogany Town. North of town, Team Rocket charges a toll at the Route 43 gate, and the Lake of Rage is full of Gyarados forced to evolve. Stop the red one, then join Lance in the hideout under Mahogany's souvenir shop: get past the cameras and traps, learn the passwords, beat the executives and make the Electrodes faint for HM06 Whirlpool. Pryce's gym is an ice floor to slide across for the Glacier Badge. The fishing guru by the lake measures your Magikarp against the record.

Team Rocket then takes over Goldenrod's Radio Tower. Fight up to the fake director for the Basement Key, open the Underground's locked door, work the switches past your rival to free the real director in the warehouse, and use his Card Key to reach the executive on the top floor. The director gives you the Clear Bell. East of Mahogany, Route 44 leads into Ice Path: push a boulder down a hole so it stops your slide on the ice below, and come out in Blackthorn City. Clair's gym hides its way forward behind boulders that fall from the floor above. Beat her, pass the elder's test in the Dragon Shrine for the Rising Badge, and receive a Dratini that knows Extremespeed. The Move Deleter makes a Pokémon forget a move.

Routes 45 and 46 lead south from Blackthorn back to Route 29. In Ecruteak, the Clear Bell convinces the sages to let you into Tin Tower, where Suicune puts you to the test. After the League, Tin Tower's upper floors lead to Ho-Oh, and the Whirl Islands hide Lugia for a trainer with the Silver Wing.

On Route 40, the Battle Tower takes a party of three different Pokémon holding different items into a Battle Room of the level you choose, against seven trainers in a row. Win them all for five of a random vitamin. Between battles you can save and quit, and the receptionist picks up where you left off.

Kanto, the League, Olivine's port and the S.S. Aqua, the Day-Care's Eggs, trade evolutions, the Pokégear's radio, the Pokédex's area view, search and other list modes, and audio are still being ported. Unported neighboring areas appear at the edges but cannot be entered yet.

Run

Requires Node.js 22.12 or newer.

npm ci
npm run dev

Open the printed local URL and select your uncompressed English US/Europe revision 1.1 ROM (.gbc, 2 MiB). Its checksum is verified locally. ROMs are never uploaded or stored in browser storage; select yours again after reloading to resume. A new game starts with Professor Oak's introduction, where you choose your character, set the clock and pick a name.

Use onscreen controls, or focus the game screen and use arrows to move, X to interact and X / Z to continue dialogue. Settings changes these keys and the text size for this browser. In choices, Up / Down change the answer, X confirms and Z answers No. Sessions save every 10 seconds and when paused. Switching apps pauses play. Download a backup before clearing browser data.

Native saves are separate from emulator snapshots and cartridge .sav files. Saving during a scene keeps the progress from before it, so the scene replays after loading. The time you give Oak is kept as an offset from the device clock (the steppers start at the device's time), and the weekday you give Mom as an offset from that clock's weekday. The tile counter measures in-game movement, not real-world steps.

Reference emulator

During development, open /reference.html to run the original game for comparison. It has separate saves and does not run inside the native player. Reference tools and the emulator are excluded from the default build.

npm run build             # Native application in dist/
npm run check:release     # Check the native distribution
npm run build:reference   # Optional reference in dist-reference/

Serve dist/ through an HTTPS static host, or use npm run preview locally. Over HTTPS the app can be installed from Savegames (or Safari's Add to Home Screen) and opens offline; select the ROM at each launch. Updates wait until you choose Update. Subdirectory hosting is supported with npm run build -- --base=/Crystal/. Use HTTPS from another device; ROM verification and save locking require a secure context.

Development

npm test
npx playwright install chromium webkit
npm run test:e2e
npm run check:vendor

Local-ROM tests use Pokemon - Crystal Version (UE) (V1.1) [C][!].gbc at the root, or CRYSTAL_ROM_PATH. They skip when absent; no test downloads a ROM. Game files, private reference builds and gameplay screenshots must remain ignored.

CI checks run on pushes and pull requests, or manually from Actions. The workflow uses the shared docker-build runner with Node 22 in a Debian container. It installs from the lockfile, runs synthetic unit and Chromium/WebKit browser tests, builds both applications, and checks vendor integrity and native release isolation. CRYSTAL_ROM_PATH points to a verified absent file, so ROM-dependent tests skip; check:reference runs separately with the private ROM and reference build.

Private ROM checks also run on pushes to main, or manually with main selected. Set the repository Actions secret CRYSTAL_ROM_URL to a direct HTTPS download URL accessible to the runner. The job rejects redirects, verifies the 2 MiB Crystal 1.1 SHA-1, builds the pinned PRET reference with RGBDS 1.0.3, runs check:reference, then runs unit/playthrough and Chromium/WebKit gameplay/reference tests. The URL is exposed only to the download step. No ROM, reference build, save or gameplay artifact is uploaded or cached; private files and browser output are removed even after test failure. Pull requests retain the synthetic workflow. A missing or inaccessible secret fails the private job instead of silently skipping its tests. Manual-device and visual acceptance cards still require their recorded checks.

To reproduce the CI test selection locally:

CRYSTAL_ROM_PATH=/nonexistent/crystal-ci.gbc npm test -- --maxWorkers=2
CRYSTAL_ROM_PATH=/nonexistent/crystal-ci.gbc npm run test:e2e -- --workers=2

git config core.hooksPath .githooks keeps the forge's project board in step with commits: Closes #N in a message moves card N to Fait and closes it, any other #N moves it to En cours, and a commit on main without a reference adds a closed card to Fait. [no-card] skips a commit. See project-board.mjs.

The full port plan covers remaining game systems, save slots, the world map, Pokédex, internet Link, friends and optional mobile step support for egg hatching. See the architecture and routine map and verification for module boundaries and reference checks.

References: PRET documentation, wiki and source. The development reference uses binjgb under its MIT license; see provenance.

Independent project. Not affiliated with Nintendo or Game Freak.