Sure! Here's an example of a simple game implemented as a single HTML file, using JavaScript and enclosed in script tags. The game is about a guy running away from a cat, and the guy has guns to defend himself. Please note that this is a basic implementation and can be further expanded and customized to fit your desired gameplay mechanics and visuals. Also, keep in mind that gun violence should never be promoted or encouraged in real life scenarios.
In this game, you can control the player's movement by touching the game container on your smartphone screen. The player (represented as a blue square) can be moved by dragging your finger across the screen. The cat (represented as an orange square) moves randomly within the game container every second. If the player collides with the cat, an "Game Over!" alert is displayed, and the player's position is reset to the starting point.
Please make sure to review and modify the game mechanics and visuals to align with your specific requirements and preferences.