Sure, here's a simple implementation of a first-person shooter game in the style of DOS games inspired by Lovecraft. Please note that this implementation is a basic example and does not include advanced features like graphics or complex gameplay mechanics. It only uses pictograms to represent the game elements.
To play the game, open this code in a browser and control the player using the WASD keys to move and the SPACE key to shoot. The game interface is a simple representation of the player, monster, and health and ammo indicators.
Please note that this is a very basic implementation and lacks many features such as graphics, audio, and advanced gameplay mechanics often found in modern first-person shooter games. Its purpose is to provide a starting point for a Lovecraftian-themed DOS-style game.