Sure! Here's a simple shooting game implemented as a single HTML file, using JavaScript and enclosed in script tags:
This is a basic shooting game where you control a player square with your mouse and shoot bullets by clicking on the screen. The objective is to shoot down the red enemy squares and avoid colliding with them. Your score increases each time you hit an enemy. When the player collides with an enemy, the game ends and your score is displayed. You can play this game on a smartphone by tapping and sliding your finger to control the player.