Sure! Here's an example of a simple game where you can destroy watermelons using different weapons. Since you mentioned smartphone operation, I'll optimize it for touch-based interaction and use pictograms for the weapons selection.
Here's the code for the single HTML file:
To play the game, open the HTML file using a web browser that supports JavaScript, such as Chrome or Firefox, on your smartphone. Touch the screen to shoot watermelons and swipe left or right to switch between different weapons (shown as icons). The objective is to destroy as many watermelons as possible and increase your score.
Remember to save the code into a file with the `.html` extension (e.g., `watermelon_game.html`) and open it with a browser to play the game.