Sure! Here's an implementation of the game as a single HTML file with JavaScript:
To play the game, simply open the HTML file in a web browser on your smartphone. You'll see a canvas with a gun at the bottom, and slimes will start descending from the top. Tap/click on the slimes to shoot them and earn points. You can use the points to upgrade your gun by tapping/clicking on the options listed in the shop.
Note: The game may need some additional styling and improvements to enhance the gameplay experience.