Creating a Tetris clone using JavaScript involves setting up an HTML structure for the game board, using CSS for styling, and implementing the game logic with JavaScript. First, create a 10x20 grid for the game board. Define Tetromino shapes and their rotations using arrays. Implement a game loop with setInterval or requestAnimationFrame to handle the falling of Tetrominoes. Add event listeners for keyboard inputs to move and rotate the pieces. Implement collision detection to ensure Tetrominoes stop at the bottom or when they hit other pieces. Write logic to clear filled lines and update the score. Finally, track the score and increase the game's difficulty as the player progresses.