Sure! Here's a simple parkour game implemented as a single HTML file with JavaScript.
This game uses a canvas element to draw the game environment. The player is represented by a red rectangle and the obstacle is represented by a blue rectangle. The objective is to avoid colliding with the obstacle for as long as possible. The game score increments with time. Use the up, down, left, and right arrow keys to control the player's movements.
Please note that this is a simple implementation and can be expanded upon with additional features and graphics.