Sure! Here's an example of a simple shooter game implemented as a single HTML file using JavaScript. It includes enemies and one teammate for the player. It's optimized for smartphone operation and uses pictograms for visual elements.
The game uses touch controls for movement. You can drag your finger across the smartphone screen to move the player around. The objective is to collide with the red enemy to increase the score while avoiding collision with the green teammate. The game will end when you collide with the teammate, and a pop-up alert will display your final score.