Sure, I can help you create a simple game using JavaScript enclosed in script tags within a single HTML file. Since Friday Night Funkin' is a popular rhythm game, I'll provide a simplified version of similar gameplay.
Here's an example implementation:
This code sets up a simple canvas, allows the player character to move left or right using keyboard arrow keys, and constantly redraws the game state. The game begins as soon as the page loads, and players can control the character on their smartphone by tapping on the appropriate sides of the screen.
Note that this is a basic example meant to demonstrate the basic game mechanics. You can expand upon it to add more features, levels, animations, and sound effects, following the structure provided.