•	The score on the top left of the screen should increase of one point for each alien destroyed.
•	A health point should be removed for each alien passing the ship’s “horizon”
•	A health point should be removed for each collision of an alien with the ship
•	When the health points reach the count of zero, the game should stop and display a game over screen with the score. Users should be able to decide whether quit the game or retry.
•	(plus) The current game difficulty is represented by the velocity and frequency of alien spawn. You may implement a way to handle such difficulty. Starting from an easy setup, shifting toward a more challenging game.
•	Store in an arbitrary file information regarding user inputs and score. Other information such as the total played sessions and total played time should be stored.
•	(plus) Upload such data in a local database or remote database or remote system (azure, amazon S3, …)