SKILL LEVEL:
<F1>			PRACTICE
<F2>			ROCK APE (EASY)
<F3>			AVERAGE
<F4>			MASTER
PRACTICE level gives access to LEVEL 1 only. This mode allows you to get used
to the movements and functions of each button.
ROCK APE level gives your ship a relatively low top speed. There is
also a low intensity enemy fire.
AVERAGE and MASTER settings give your Ship high speed, amidst an agressive
enemy.
F5	End of game			F6	Relative Joystick Control
F7	Absolute Joystick Control	F9	Music On/Off
F10	Pause				Space	Fire

Relative Control:
LEFT/RIGHT	Rotate Left/right
UP/DOWN		Accelerate/Decelerate

Absolute Control:
LEFT/RIGHT	Left/Right
UP/DOWN		Up/Down