The hidden secret Easter Egg revealed in the Nightly build of Mozilla Firefox web browser is a “Pong” game featuring a flying and colorful unicorn. The unicorn, if you remember made its first appearance long time back in another Easter Egg.

Play Unicorn game in Firefox Nightly Build

First things first. Open the Customize window of Firefox. For this, right-click the hamburger icon visible in the top-right corner of the browser window and select “Customize” option. Having done this, you’ll need to move all buttons present in the toolbar customize window to the main toolbar.

In short, you need to empty the customize page by dragging-n-dropping all existing items to Firefox toolbar.

When finished, the hidden secret Easter Egg will make the appearance. You’ll notice a new “Unicorn” box/button added next to the “Density” drop-down box.

Click on the “Unicorn” button, and it’ll launch the secret “Pong” game. It is reminiscent of the classic “Jardinains” game. You can play the game by simply moving the upper “Flexible Space” item with the help of left/right arrow keys. The lower “Flexible Space” item is controlled by Firefox. Once you are done with it, you can restore all default toolbar buttons and remove extra buttons by again going to “Customize” page and clicking on “Restore Defaults” button. That’s it! Let us know if the trick works for you and share your experience with us in the comments section below. TIP: You can also play the built-in T-Rex Dinosaur game in Chrome browser when offline.