Sure, here's an example of a simple retro-style game implemented as a single HTML file using JavaScript. Since you mentioned smartphone operation, I'll make it a touch-based game with pictograms.
🕹️
In this game, the main element with id "game" displays a game controller pictogram (
🕹️) and the current score. The game starts automatically and increments the score every second. The player can touch the screen to pause and resume the game.
Please note that this is just a simple example to demonstrate the concept. You can further enhance the game by adding more gameplay elements, levels, or graphics based on your requirements.