Sure, here's an example of a simple Pokemon-themed game implemented as a single HTML file using JavaScript. The game can be played on a smartphone and uses pictograms for the Pokemon characters.
Pokemon Battle!
When you open this HTML file in a web browser, it will display three Pokemon images (Pikachu, Charizard, and Squirtle) as buttons. By clicking on one of the Pokemon, the game will randomly select an opponent's Pokemon, display both Pokemon in the battle log, and declare a winner based on a random chance. You can continue playing by selecting a different Pokemon.