If you use Chrome, it's likely you've seen the 2-bit dinosaur that appears when your computer is not connected to the internet. It's an infinite runner game. The object is to jump over oncoming cacti and duck under pterodactyls. To play it while you are connected to the internet, copy and paste
chrome://dino/ into the address bar of Chrome. Spacebar starts the game, then use up and down arrows to jump and duck.
Here's someone who taped a photoresistor to their display. When it senses a cactus, it triggers a servo to press the spacebar. What happens when it sees a pterodactyl, though?