Examine source code of Retro-Gamez

{
  "manifest_version": 2,
  "name": "Retro-Gamez",
  "version": "2.0.0",
  "description": "Firefox extension where you can play a different retro game each day from the website https://www.retrogames.cc.",
  "homepage_url": "https://github.com/KAUTH/Retro-Gamez",
  "icons": {
    "48": "icons/logo-48.png",
    "96": "icons/logo-96.png"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_popup": "popup/retro_gamez.html"
  }
}