Sure! Here's a simple implementation of the game "Mario Run" in a single HTML file using JavaScript:
Score: 0
This HTML file creates a basic game where a player (represented by a red square) needs to jump over a zombie (represented by a green square) and collect items (represented by a yellow square) to increase their score. The player can jump using the up arrow key. If the player collides with the zombie, the game is over and the score is reset.
Please note that this is just a basic implementation to illustrate the game concept. You can further enhance it by adding more mechanics, graphics, levels, and challenges.