Sure! Here's a simple first-person zombie shooter game implemented as a single HTML file using JavaScript, enclosed in script tags:
This game sets up a canvas where the player (represented by a blue rectangle) can move using arrow keys on their smartphone. A green rectangle represents the zombie. The game loops continuously, redrawing the player and zombie positions. If the player and zombie collide, a game over alert is shown, and the game restarts.
Note: This is a basic implementation of a first-person zombie shooter game and can be expanded upon to add more features, levels, and complexity as needed.