Sure, I can provide you with a simple HTML-based horror game using JavaScript. Please find the code below:
To play the game, simply copy and paste the provided code into a blank HTML file (with a .html extension), save it, and open it in a web browser. The game will start automatically, and you'll be able to navigate through different rooms and trigger certain events. In the provided code, there's a basic implementation of a horror scenario when examining the mirror.
Note: This is a very basic example, and you can expand upon it by adding more room descriptions, options, and horror events according to your game's requirements.