Here's an example of a working clock implemented as a single HTML file, using JavaScript and enclosed in script tags. The clock is designed to be playable as a game on a smartphone, with the use of pictograms:
This implementation includes a clock that updates every second, taking the current time from the user's device. It also allows the user to input a specific hour and minute combination, and when the submit button is clicked, an alert message is displayed with the entered time. You can then add your game logic based on the entered time.