Sure, here's a simple Tetris game implemented as a single HTML file using JavaScript:
You can copy and paste the above code into a file with a .html extension, and then open it in a web browser to play the Tetris game. The game is designed to be played using keyboard controls (left arrow key to move left, right arrow key to move right), but you can modify it to support smartphone touch controls if needed. The game uses simple square blocks to represent Tetris pieces, but you can replace them with pictograms if desired.