Sure! Here's an example of a simple platformer game in a single HTML file using JavaScript:
In this game, you control a stickman represented by a black square. The stickman can move left and right using the left and right arrow keys on the keyboard respectively. The goal is to collect all 10 hidden gems represented by pictograms in the form of PNG images. When the stickman collects a gem, it disappears, and once the player collects all 10 gems, a congratulations message will be displayed, and the game will reset.
Please note that you need to replace `emozi_cat.png` with your own image path and add more gem elements by duplicating the existing gem element and adjusting the `left` and `top` positions to hide the gems around the platform.
Feel free to customize and enhance the game further according to your preferences!