Sure! Here's a simple example of a parkour game implemented as a single HTML file using JavaScript. The game features a green cat as the character, and you can control it by pressing the spacebar to jump and the left and right arrows to move.
To play the game, simply save the above code in a file with a `.html` extension, open it in a web browser, and play by using the left and right arrows to move the green cat character and the spacebar to make it jump. Enjoy your parkour game!