Sure! Here's a simple game implemented in a single HTML file that meets the provided requirements:
In this game, you control a squirrel using the arrow keys to keep it within the camera (game container). The squirrel moves downwards, and if it reaches the bottom of the camera or collides with an obstacle, the game is over.
Obstacles start appearing at level 10, and the game continues endlessly. Each level is indicated by an incremented level variable. If the squirrel collides with an obstacle or reaches the bottom, the game is reset, and the player can play again. The game uses pictograms for the squirrel and obstacles.
You can copy the above code into a single HTML file, save it with a .html extension, and open it in a web browser to play the game.