Sure, I can provide you with a basic template for a text-based horror game set in the "Backrooms". Please keep in mind that this is a very simple implementation for the purposes of this example. Feel free to enhance it further as you see fit.
To play the game, simply open the HTML file on a supported browser, and you will be presented with the initial room description. Enter the appropriate input based on the available options displayed in the description, and press "Submit". The game will process your input and display the next room description accordingly.
Please note that this is a very basic implementation and can be expanded upon with additional features, graphics, sound effects, and more elaborate gameplay mechanics.