Sure! Here's an example of a game implemented as a single HTML file using JavaScript:
In this game, you can spawn different types of creatures by tapping on the spawn menu. The creatures include "a90" (attacks a random creature on screen with massive damage), "human" (moves around the screen), "rush" (moves quickly towards something and kills it on collision), "ambush" (moves fast and kills anything it touches), and "dupe" (damages any creature that opens a door spawned on it).
The game uses a canvas element to draw the game graphics and updates the game state 60 times per second. You can also spawn creatures by pressing the Enter key.
Please note that this is a basic example and there is room for improvement and expansion based on your specific requirements and preferences.