Sure! Here's an example of a simple platformer game implemented as a single HTML file using JavaScript and enclosed in script tags:
To play the game, you can open the HTML file in a web browser, and you will be able to control the player (represented by a blue square) using the left and right arrow keys to move and the space bar to jump. The player needs to navigate through the brown platforms to reach the goal (the top platform) while avoiding falling off the screen.