Atari Arcade

Atari 800 XL game library for the browser (desktop + mobile PWA), powered by AltirraSDL — a WebAssembly port of Avery Lee's cycle-accurate Altirra emulator.

Layout

• index.html — game picker (grid, search, PWA entry point)
• games.json — game list; each entry maps a display name to a file in emu/library/
• emu/AltirraSDL.{html,js,wasm,data} — prebuilt emulator (from the AltirraSDL nightly release, AltirraSDL-*-wasm.zip)
• emu/config.json — same-origin firmware bundle + "⬅ Games" back-link
• emu/library/ — the .atr disk images; launched via ?lib=<file>
• firmware.zip — Atari OS/BASIC ROMs, fetched automatically on first run
• sw.js, manifest.webmanifest, icons/ — PWA install + offline cache
• .github/workflows/deploy-pages.yml — GitHub Pages deploy with cache-bust and deploy-time stamping

Adding a game

1. Drop the .atr (or .xex/.car/.cas) into emu/library/
2. Add { "name": "Game Name", "file": "GameFile.atr" } to games.json
3. Commit + push — the deploy workflow does the rest

Updating the emulator

Download the latest AltirraSDL-*-wasm.zip from the nightly release and replace the four AltirraSDL.* files in emu/.

Deploy

Pushes to main deploy automatically via GitHub Pages (Settings → Pages → Source: GitHub Actions). The picker footer shows the exact deploy time and commit, and the service worker cache is busted on every deploy.

License / attribution

The emulator under emu/ is AltirraSDL by Jakub Dębski, a portable fork of Altirra by Avery Lee, licensed GPLv2 (see emu/LICENSE). The vendored bundle is built from upstream commit 27d37558; its corresponding source is the upstream repository at that commit. Our modifications to the emulator's host page (the ARCADE-PATCH block injected into emu/index.html, source in scripts/emu-autofullscreen.snippet.html) are published in this repository under the same GPLv2 terms.

Everything else in this repository (picker, service worker, scripts) is separate from the emulator and not covered by the GPL. Game images under emu/library/ are the property of their respective copyright holders, preserved via Homesoft.

Local patches to the emulator shell

emu/index.html carries an "ARCADE-PATCH" block (source: scripts/emu-autofullscreen.snippet.html) that activates on ?lib= launches:

• Arcade chrome — hides the desktop bar from the first frame; ⌄ toggles a compact START/SELECT/OPTION/RESET row, ☰ opens the menu, ⛶ appears while not fullscreen.
• ?fs=1 — a tap enters browser fullscreen (retried on end-of-gesture events until it takes).
• TILT toggle + ?tilt=1 — device-orientation steering (extra sensitivity on forward/back so the screen stays visible while accelerating).
• AUTO FIRE slide switch — pulses the trigger at ~11 Hz via ATWasmSetJoystick.
• ?tv=1 — smart-TV remote controls (CE-HTML/HbbTV key codes): D-pad → joystick, OK → fire, Red/Green/Yellow → START/SELECT/OPTION, Blue → auto-fire, Play/Pause → pause, Back → picker. Open the picker with ?tv=1 and every launch inherits it.
• Analytics — GoatCounter (atari-arcade.goatcounter.com), cookie-less. Game launches report as /play/<Game>, so the dashboard's Paths view doubles as a per-game popularity table.

After replacing the AltirraSDL bundle files, re-apply with:

./scripts/patch-emu.sh