Sure, here's a simple implementation of the classic game "Snake" with a twist of adding a gun element. The game will be optimized for smartphone operation and will use pictograms to represent the game elements. Save the code below in a file with a `.html` extension and open it in a web browser to play the game:
In this game, you control the snake using the arrow keys on your smartphone's keyboard. The snake will move in the specified direction each time you press an arrow key. Additionally, you can shoot by pressing the spacebar. The aim is to collect gun ammos represented by red blocks while avoiding collisions with the snake's body or the game boundaries. Each collected gun ammo will increase your score. The game ends if the snake collides with itself or the boundaries.
Please note that this is a simplified version of the game with limited features. Feel free to expand and customize the game as per your requirements.