Sure, here's an example of a simple platform game implemented as a single HTML file using JavaScript. The game will be playable on a smartphone and will use pictograms for graphics:
This code creates a platform game where the player, represented by a black rectangle, can jump on a blue platform to avoid falling off the screen. The player can jump by tapping the screen on a smartphone or by pressing the spacebar on a computer keyboard. The game uses the HTML `canvas` element to render the graphics and is enclosed within the `script` tags.