Sure, here's a playable, text-based game implementation of a cowboy-themed game set in a realistic town in the 1890's. It includes a gun system and some gory elements, all within a single HTML file enclosed in `script` tags:
In this game, you play as a cowboy in a wild west town. The goal is to shoot the outlaw enemy before they shoot you. Your health and ammo are displayed in the console. Each time you shoot, there is a random damage calculation for both you and the enemy. The game continues until either you or the enemy runs out of health.