Sure! Here's an example of a simple sandbox game implemented as a single HTML file with JavaScript:
This simple sandbox game allows you to control a player (represented by a blue square) on a canvas using touch events. You can drag your finger on the canvas to move the player around. The game loop continuously redraws the canvas, updating the player's position based on touch events.
Feel free to modify and expand upon this code to create your own custom sandbox game using pictograms or any other elements you'd like.