PuffyEngine

PuffyEngine is a tiny (< 400 KB) single-file C++ launcher that embeds a Chromium-based Steam HTMLSurface browser in a native Windows window with keyboard, mouse, and gamepad support. Because it uses Steam’s Chromium layer, you get many modern browser features (HTML5, CSS, JavaScript, audio/video, etc.) without shipping a big runtime yourself.

Created by coeurnix, licensed under the Boost Software License 1.0.

Requirements

• Windows only
• Steam required and must be running (i.e. suitable for making Steam games)

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How it works

• Starts a local HTTP server on 127.0.0.1:<port> (default 19996).
• Serves static files from a /game directory (default ./game/ next to the executable).
• Opens a Chromium-based Steam HTMLSurface pointed at that server.
• Forwards keyboard, mouse, and XInput gamepad to the web page.
• Exposes Steam features (achievements, stats, cloud saves) to JavaScript via a simple alert-based bridge.

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Project layout

Typical layout:

PuffyEngine.exe
/game
  index.html
  main.js
  assets/...

You can override the game folder and other settings:

• --puffyport <port> – HTTP port (default: 19996)
• --puffydir <path> – game folder (default: ./game/)
• --puffywidth <pixels> – window width (default: ~80% of screen)
• --puffyheight <pixels> – window height (default: ~80% of screen)

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JavaScript bridge (callbacks)

PuffyEngine listens to alert() messages that start with puffy: and interprets them as engine commands.

Basic examples:

// Exit the game
alert('puffy:exit');

// Toggle fullscreen
alert('puffy:setFullscreen(true)');
alert('puffy:setFullscreen(false)');

// Show/hide cursor
alert('puffy:setCursorVisible(false)');
alert('puffy:setCursorVisible(true)');

// Achievements and stats
alert('puffy:grantSteamAchievement("ACH_WIN_ONE_GAME")');
alert('puffy:grantSteamStat("total_deaths", 1)');
alert('puffy:grantSteamStat("playtime_hours", 0.5)');

Steam Cloud helpers:

// Load a file from Steam Cloud, then receive it in a callback
function onCloudLoaded(text) {
  if (text === null) {
    // no save found
    return;
  }
  // parse and apply save data
}
alert('puffy:requestSteamCloudSave("save.json","onCloudLoaded")');

// Save text data
alert('puffy:saveToSteamCloudSave("save.json","some serialized data")');

// Delete a cloud save
alert('puffy:removeSteamCloudSave("save.json")');

All these commands are transported via alert("puffy:..."), parsed natively, and never shown as real UI dialogs.

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Building

You need a Windows toolchain, Steamworks SDK (for steam_api64.lib and headers), and the usual Windows libraries (linked in the source).

Easiest (Windows)

From a Developer Command Prompt:

build.bat

With CMake

Using the provided CMakeFiles.txt:

cmake -B build -S .
cmake --build build --config Release

Copy the resulting executable next to a /game folder and run it while Steam is running.

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License

This project is released under the Boost Software License 1.0.