[2023-08-30Update] adjust difficulty, add HUD and some particle effects

Significant changes have taken place in this version of TGES! Have fun!

1. "Magazine Mechanism" for player's gun. Now you can no longer just fly into the sky and never fall back with the help of the gun.

2. HUD for the magazine mentioned above. It will be a reliable companion in your future fight.

3. Euler Bombers (flying enemies) now have higher speed than the player. Now you cannot just run away! Prepare to confront your enemies.

4. Add trail particles for player's bullets. It's tangent graph!

5. Fix known bugs.