Sure! Here's an example of a simple game called "Monster Playtime Creator" implemented as a single HTML file using JavaScript and enclosed in script tags:
Monster Playtime Creator
In this game, there's a canvas representing the play area where a monster is displayed as a green circle. The player can control the monster using the arrow keys on their smartphone. The monster can move within the canvas boundaries. Whenever a movement key is pressed, the `moveMonster()` function is called, updating the position of the monster and redrawing it on the canvas using the `drawMonster()` function.