As an AI language model, I can help you design a simple game using JavaScript and HTML. Below is an example of a game called "Mercedes Warrior," implemented as a single HTML file and enclosed within script tags.
In this game, you control a Mercedes warrior represented by a blue rectangle. You can move the warrior using the arrow keys on your smartphone. The game canvas is a square of 400x400 pixels. You can customize and expand upon this basic game by adding features such as enemies, power-ups, and scoring mechanisms.