Sure, here's a simple shooting game implemented as a single HTML file using JavaScript:
Shooting Game
This game allows the player to control a blue square at the bottom of the canvas using the left and right arrow keys. The player can shoot red bullets by pressing the spacebar. The bullets will travel upwards, and once they reach the top of the canvas, they will be removed from the screen.
To play the game, you can copy the above code into a new HTML file and open it in a web browser. The game canvas will appear along with the player character. Use the arrow keys to move the player and press the spacebar to shoot bullets.