Sure! Here's an example of a simple Tetris game implemented as a single HTML file using JavaScript and enclosed within script tags:
To play the game, you can copy the code and save it in a file with the `.html` extension, then open it in a web browser (preferably on a smartphone) to start playing! The game will run automatically, and you can use the arrow keys to move and rotate the falling tetromino pieces. The goal is to fill complete horizontal lines on the grid to score points and prevent the tetromino pieces from stacking up and reaching the top.
Note: This is a simplified implementation of Tetris using simple shapes and basic mechanics. It may not have all the features and complexities found in complete Tetris games, but it should give you a good starting point. Feel free to modify and enhance it as per your requirements.