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itch-html5-package

Skill1 starsChanged 6 days agoMITView on GitHub

Check an HTML5/web game build against itch.io's rules and package it as a correct upload zip. Catches file-name case mismatches that work on Windows/macOS but 403 on itch, absolute "/" paths, http:// requests, index.html in the wrong folder, the 1,000-file / 500 MB / 200 MB / 240-char limits, shipped source files and a missing viewport tag. Use when publishing or updating a web game (three.js, Phaser, PixiJS, Godot/Unity/GameMaker web exports, plain canvas) on itch.io, or when an itch HTML5 game shows a black screen or 403 errors.

The file

We split this skill into the rules it gives an agent

1 rule. About 0 are common, 1 is distinctive, and 0 are very specific to this project.

  • ≈0

    Common · estimate

    Many files like this have a rule of this kind.

  • ≈1

    Distinctive · estimate

    This author's own choices. Worth a look.

  • 0

    Very specific

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  • Common
  • Distinctive
  • Very specific
  1. Distinctive:

    Case-sensitive names: Every path referenced in HTML, CSS, JS and JSON is resolved, and a reference that only matches with different …

    line 21

≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

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Files
SKILL.md

itch-html5-package

scripts/itch-package.mjs is zero-dependency Node 22+.

node itch-package.mjs ./build                 # check, then write ./build-itch.zip
node itch-package.mjs ./build --out game.zip
node itch-package.mjs ./build --check          # report only

It exits 1 and writes no zip if anything would break on itch. Fix the ✘ items and run again. Warnings (!) are worth reading but don't block.

What it checks (itch.io's documented rules)

  • index.html exists, named exactly that. If it's one folder down (you zipped the parent folder), that folder becomes the root.
  • ≤ 1,000 files, ≤ 500 MB extracted, ≤ 200 MB per file, paths ≤ 240 characters.
  • Case-sensitive names. Every path referenced in HTML, CSS, JS and JSON is resolved, and a reference that only matches with different capitalization is an error. Windows and macOS hide this; itch's servers return 403.
  • Relative paths only. /assets/x.png fails because itch serves the game from a subfolder.
  • External requests must be https.
  • Shipped source files (.psd, .blend, .aseprite …), no viewport meta, and the YouTube Playables SDK, which hangs inside itch's iframe.

It can't see paths built at runtime ('level' + n + '.json'). Spot-check those by hand after upload.

Uploading

On the itch.io project page: Kind of project → HTML, upload the zip, tick "This file will be played in the browser", and set the viewport size (or enable "Mobile friendly" and fullscreen for phone games). HTML5 games only take payments as donations; selling needs a downloadable build.

Engine notes

  • Godot 4 web exports need SharedArrayBuffer unless exported with thread support off. On itch, enable "SharedArrayBuffer support" in the embed options, or export single-threaded.
  • Unity builds with Brotli (.br) are served correctly by itch. Gzip works too.
  • A single self-contained .html file can be uploaded directly, with no zip.

Download now (ZIP)

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