Sure! Here's an example of an HTML file that implements a game where a square moves in a box and gets creepier over time:
In this game, a square moves randomly within a 400x400 pixel box. Every 5 seconds, the background color of the box becomes 5% darker, giving a creepy effect. The square's position is updated every time it moves, and the corruption percentage increases every 5 seconds. The game continues indefinitely, making the square and background progressively creepier over time.