17 MAR 2020:
- Added a way to adjust the sound up and down at the title screen.
- The enemy now shoots even if the player stays idle.
- Some of the enemy ships move around the screen based on the player's position and their current health. If the enemy ship is near full health, they'll aggressively chase the player. If the enemy ship is wounded it will retreat away from the player. This part especially is a work in progress as I experiment with other movement logic to see what works best.