DESC
In Alien Invasion, the player controls a ship that appears at
the bottom center of the screen. The player can move the ship
right and left using the arrow keys and shoot bullets using the
spacebar. When the game begins, a fleet of aliens fills the sky
and moves across and down the screen. The player shoots and
destroys the aliens. If the player shoots all the aliens, a new fleet
appears that moves faster than the previous fleet. If any alien hits
the player’s ship or reaches the bottom of the screen, the player
loses a ship. If the player loses three ships, the game ends.


TODO

Establish permanent sprites (Ship, Aliens, Bullet)

Design menus
Implement menus

Design ship upgrades UI
Implement ship upgrades UI

Seperate points and upgrade currency
Create currency location in scoreboard

Implement different alien ship types and attributes

Redesign difficulty scaling for different worlds, levels, and aliens

Create and Test sounds for shots and hits
Create and implement background music