Second game I made

This is a Space Shooter game. In this game, the player needs to achieve 400 score to summon the boss and defeat him. Score will keep decreasing overtime and player will lose the game if score reaches to -20. Player have a sheild which is a in-game player action which acts as deflector for enemy bullets and also gets no damage when colliding with enemies. There are also normal bullets, rockets, bullet ammo, health pack, ammo pack. Rocket use is limited in this game.

These are the images of the codes I struggled solving. The shield function at the beginning was hard to understand for me and after fully understanding how boolean code works, I managed to solve it quickly. Other problem is when the player collides with the boss, the amount of damage the player receives is too much. Hence I had to solve it by using a cooldown for the boss collision.