This is Dinosaur Game, similar to the one found in Chrome's offline page. But this isn't any old Dinosaur Game, it's a PWA!

We developed the game in Windows format on Unreal Engine.

This Easter Egg is usually hidden on the No Internet connection error page in Google's Chrome web browser and played offline. Here, however, you can play the hacked Dino T-Rex Runner Game online and compete with other players. Press the space bar to start the game. Use the up and down arrow keys to control the dinosaur. Try to score the maximum points.