Sure, here's an example of a simple game implemented as a single HTML file using JavaScript and enclosed in script tags:
Picture Guessing Game
Guess the correct pictogram by tapping on it:
In this game, you'll see a set of pictograms displayed on the webpage. The goal is to guess the correct pictogram by tapping on it. If you make the correct guess, an alert will congratulate you and the game will restart with a new target pictogram. If your guess is incorrect, an alert will notify you to try again.
Note: The game will be playable on any device with a browser, not only smartphones. It uses basic HTML and JavaScript to achieve the functionality.