2D shooter Update

This is my 2D Shooter project (second version). I made the following significant modifications:

1. Adding different types of enemies (e.g. Boss)
2. Adding two interesting, comprehensive, and coherent levels
3. Adding new obstacles (Rocks, Black Hole, planets)
4. Adding unique moving behavior for rocks and planets
5. Adding two game mechanics （Black holes, planets, and meteorites can cause devastating damage to players and enemies that touch them）
6. Adding useful instructions
7. Adding Mini map
8. Modifying Game UI (Main Menue, Mission Complete page)

Credits:

Created by Xiaokun Chen