Sure! Here's an example of a 2-D platform runner game implemented using JavaScript and enclosed in script tags in a single HTML file:
Please note that this is a basic template and does not include the full implementation of all the game mechanics, enemy interactions, etc. You can expand on this code to add more features, levels, and enemies as per your requirements. Additionally, you can use pictograms or sprites to represent the player, enemies, and other elements in the game.