Sure, here's an example of a simple game implemented in a single HTML file using JavaScript. This game is called "Guess the Pictogram!" and is designed for smartphone operation.
In this game, you need to guess the correct pictogram based on the displayed question mark. The available pictograms are represented using emojis. You can enter your guess in the input field, and then click the submit button or press Enter to submit your answer. The score will increase if your guess matches the correct pictogram, and a new round will begin with a different pictogram to guess.
Feel free to customize and enhance the game as per your requirements.