Examine source code of Web Invaders

{
  "manifest_version": 2,
  "name": "Web Invaders",
  "short_name": "",
  "version": "1.1resigned1",
  "author": "fzilla",
  "description": "Web Invaders is a game which can be played on websites.",
  "developer": {
    "name": "Samar Yalini",
    "url": "https://github.com/yaliniyalu"
  },
  "applications": {
    "gecko": {
      "id": "web-invaders@fzillaweb.com",
      "strict_min_version": "42.0"
    }
  },
  "icons": {
    "48": "/assets/icons/icon.png",
    "96": "/assets/icons/icon@2x.png",
    "144": "/assets/icons/icon@3x.png",
    "192": "/assets/icons/icon@4x.png"
  },
  "browser_action": {
    "browser_style": false,
    "default_area": "navbar",
    "default_icon": {
      "64": "/assets/icons/icon-store.png"
    },
    "default_title": "Web Invaders"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "web_accessible_resources": [
    "/assets/images/rocket.png",
    "/assets/images/rocket-inactive.png",
    "/assets/images/virus.gif",
    "/assets/images/virus-2.gif",
    "/assets/images/bullet.png",
    "/assets/images/bomb.png",
    "/assets/images/explosion.gif",
    "/assets/audio/explosion.mp3",
    "/assets/audio/explosion-1.mp3",
    "/assets/audio/shoot.mp3",
    "/assets/audio/background.mp3",
    "style.css",
    "/assets/fonts/beholder.regular.ttf",
    "/assets/fonts/forvertz.regular.ttf",
    "/assets/fonts/inria-sans.regular.ttf",
    "/assets/fonts/soccer-league.regular.ttf",
    "/assets/fonts/herkules.ttf"
  ],
  "options_ui": {
    "page": "options.html"
  },
  "permissions": [
    "<all_urls>",
    "webRequest",
    "webRequestBlocking",
    "storage"
  ]
}