Here's an example of a simple game called "Doctor Vet: Lumpy Touch" implemented as a single HTML file with JavaScript:
Doctor Vet: Lumpy Touch
In this game, you'll see a game screen with a dog pictogram (represented by
🐶) called Lumpy. The goal is to touch/click on Lumpy as many times as possible within the time available. Each touch/click increments the score, and Lumpy's position is randomized after each touch. The score is displayed at the top of the page.
You can play the game by opening the HTML file on a browser, preferably on a smartphone for a better touch experience.