Sure! Here's an example of a simple auto running sideways scrolling beat em up game using JavaScript and HTML. Please note that this is a basic implementation and can be further developed to enhance the gameplay, graphics, and features.
In this example, the game starts with a soldier (representing the player) positioned on the left side of the canvas. The player can jump by tapping and holding on the screen, and the soldier sprite moves upwards when jumping and falls when the gesture ends. The ground is represented by a flat rectangle at the bottom of the canvas.
Please note that this is just a basic framework for the game mechanics. To turn it into a complete game, you would need to add enemy characters, combat movements, different levels with varying environments, and implement boss fights. Additionally, you could enhance the visuals, audio, and add other gameplay elements to make it more engaging.
This is just a starting point, and further development and customization would be required to turn it into a fully functional game.