Sure! Here's an example of a simple shooter game implemented using JavaScript and enclosed in a single HTML file. The game is similar to the classic game Snake, but instead of a snake, you control a shooter trying to shoot apples falling from the top of the screen.
You can copy and paste the above code into a text editor and save it as a ".html" file. Then, you can open the file with a web browser on your smartphone and play the shooter game. Use the left and right arrow keys to move the shooter and try to shoot the falling apples. The game will end when you reach a score of 100 or more.