Sure! Here's a simple example of a Mario-like game implemented as a single HTML file, using JavaScript and enclosed in script tags. Please note that this is a basic version and may not have every feature you expect in a fully advanced game.
This simple game allows the player to control a blue rectangle using the left and right arrow keys for horizontal movement, and the up arrow key to jump. The player is affected by gravity and can only jump when not already jumping or falling. The game loop continuously updates and renders the game state, providing a smooth gameplay experience.