This is a Chrome Extension. You can install it through Chrome Web Store. The extension is 100% safe, inspected by Google engeneers.
After installing, it will be shown in the top right corner.
To play it, just click on the extension. You can try it in popup and full-screen mode.
By having this you won't need to search and surf the web for coll FNF Test games.
And this works in offline mode too! :)