Sure, here's a simple Crossy Road game implemented as a single HTML file using JavaScript:
This implementation creates a canvas element where the game is displayed. The player controls a character using the left and right arrow keys, aiming to avoid colliding with obstacles that are falling from the top of the canvas. The score increases for each obstacle avoided, and the game ends when the character collides with an obstacle.
Note: The gameplay can be enhanced further by adding features such as different types of obstacles, power-ups, levels, and high scores. However, the provided code serves as a basic example to demonstrate the functionality of a Crossy Road-like game.