Sure! Here's a simple implementation of the classic Tetris game in a single HTML file using JavaScript:
Tetris
This implementation uses the HTML canvas element to render the game and captures keyboard events to control the Tetris blocks. It generates random Tetris pieces and allows the player to move and rotate them. The game loop continuously moves the current piece down and checks for collisions with the grid or boundaries. When a line is completed, it is cleared from the grid. The game ends if a new piece cannot be spawned without colliding.
Feel free to modify and enhance this code to suit your needs further. Have fun playing Tetris!