Sure! Here's an example of a game similar to Flappy Bird where something is chasing the player. It is implemented as a single HTML file, enclosed in script tags, and written in JavaScript.
This game features a bird that is controlled by pressing the Spacebar. The bird needs to avoid getting caught by the chasing object. The score increments as the bird moves forward. Once the bird collides with the chasing object, the game is over, and a "Game Over" message is displayed.
Please note that this is a simple implementation to demonstrate the concept and may require additional improvements for a complete game.