Sure! Here's a simplified version of a first-person shooter (FPS) game that you can play with a friend in 5v5 mode. Please note that this is a basic implementation and does not include advanced game mechanics like actual shooting or movement. It's just a starting point for you to build upon.
To play the game, simply copy the code below and save it as an HTML file. Then, open the file in a web browser on your smartphone:
The code sets up an HTML canvas where you can see two player rectangles, one in red and the other in blue. To control the movement of each player, touch and drag on the screen of your smartphone. The players will follow your finger movement.
Remember, this is just a basic implementation of a 2D FPS game. You can enhance it by adding shooting mechanics, level design, and multiplayer functionality. Feel free to modify and expand the code to match your desired game features.