Game
Here is a sample program for a platformer game implemented as a single HTML file with JavaScript. The game can be played on a smartphone and makes use of emojis for graphics.
In this game, you play as a smiley face that can jump and move left and right. Your goal is to reach the end of the level, which is made up of randomly generated platforms. You can jump onto and off of platforms, but if you fall off the bottom of the screen, you lose and the game restarts. Good luck!