There is one secret game in Firefox called Unicorn Pong and to play with it you need to know how to approach it.
It seems that every program is now in vogue tours to have a hidden game. Chrome has one game with the dinosaur Dino, the Edge surfs and Firefox plays with Unicorn Pong.
Of course you can also play with Firefox Unicorn. Let's see how….
Step 1. First, open Firefox. Do click in the hamburger menu (the three horizontal lines) at the top right, then click Customize.
Step 2. In the Customize Firefox tab, you'll see a list of available tools for configuring the toolbar. Click and drag all the toolbar items to the right of the "Overflow Menu" except the "Flexible Space".
Step 3. The "Unicorn" button will appear at the bottom of the window. Click on it.
Step 4. A Pong game with a small unicorn icon will appear on the left side of the tab. In this version of the game, the "Flexible Space" box serves as a Pong racket, and the unicorn icon is the ball.
To play, just use the left and right keys arrow on your keyboard to move the UP flexible space so the unicorn doesn't go through it. The bottom Pong package is handled automatically by the game.
If you lose and want to play again, just double-click the Unicorn button.
When the game is finished, click "Reset Defaults" to reset all the items you went to in the Popup menu with Step 2.