Sure, here's an example of a game where a cube bounces within a box:
In this game, a red cube is represented by a `<div>` element and it bounces within a square box. The cube's initial position is set randomly within the box. It moves by updating its position in small increments at regular intervals using a game loop implemented with `setInterval`. The cube will bounce off the edges of the box, reversing its direction when a collision occurs.
Please note that the code snippet provided above should be saved as an HTML file and opened in a web browser to play the game.