Sure, here's a simplified version of Tetris implemented as a single HTML file using JavaScript:
This HTML file creates a canvas element and uses JavaScript to handle the game logic of Tetris. You can control the game using the arrow keys on your smartphone's keyboard. The gameplay involves moving and rotating tetrominoes (the falling blocks) to form complete horizontal lines, which then disappear. The game ends when the stack of tetrominoes reaches the top of the grid.
Feel free to customize and enhance this code further to add more features, styling, or improvements to the game mechanics.