Pictures
- skyline damaged 1 and 2	ok
- skyline destroyed		ok
- buttons			ok
	- watch tutorial	ok
	- start			ok
	- try again		ok
	- credits		ok
- welcome text

Animations
- skyline saturates gradually	ok
- you win!
- you loose :(

Sounds
- grinding of cogwheels
- warm up of laser
- firing of laser
- firing of ufo lasers
- explosions
- you win!
- you loose :(

Other
- create the tutorial
- credits

Programming
- add the sprite animations
	- rotation of gun
	- rotation of gears
	- warming up of laser
	- firing of laser (where is the laser's end-point?)
	- ufo explodes
	- city explosion
- add the sound effects

