Space Invaders game clone using Object Oriented Design Patterns. This project is a perfect application of 13 Design Patterns inplemented to solve many challenging problems.

This Youtube Demos Playlist explains how the game components are implemented iteratively until achiveing the final product.

1. Factory: Creating 55 aliens without worrying about the actual implementation of each alien type.
2. Singleton: Creating managers for each system's component to easily access them.
3. Object Pool: Implementing the Aliens Grid animation which includes changing the X and Y positions for each Alien and its image when the grid is stepping right or left.
4. Proxy: A lightweight interface of the heavy alien objects. These object interfaces will expose the functions of the actual aliens but with lower cost.
5. Flyweight: To load all the characters in a shared place once the game is loaded, then ruse them to draw the texts on the screen.
6. Composite: To implement a hierarchy of game objects that are either a composition of other objects or a single object (e.g.: Aliens Grid, Aliens, Sheilds, Sheild Bricks).
7. Iterator: A standard iteration interface for multiple iteration approaches on the Game Objects Trees.
8. Command: Implementing Timer Events that can be queued and parameterized as needed.
9. Observer: Build a list of observers that will be notified when the state of the related object changes. For instance, when a ship missile hits and alien: The alien should be removed from grid, a splat effect should be displayed, the ship should be able to shoot another missile, a sound effect should be played, and player’s score get updated accordingly.
10. Visitor: Identifying the collision Game Object pairs and apply the appropriate action accordingly through a clean and scalable way.
11. Strategy: Isolating the behavior of each Bomb type and implementing the dropping animation algorithm for each category.
12. Null Object: Having an object type in an object structure that inherits the same interface but does nothing.
13. State: To control the ship’s behavior by not shooting multiple missiles at a time. Fo example, the missile should hit one of the game objects before the player can launch another missile.