During play, press any of the following:
'T'------------------For invincibility on current level
'S'-----------------------------------Speed the game up
'A'----------------------------------For all the extras
'E'---------Removes extras from ship (IE invincibility)
'R'-------------------------------Restart current level
'ESC'------------------------------------To skip levels
'1'-'6'--Select weapon and press 'SPACE' to activate it
'='-------Advance to further parts of the current level
'-'-------Go back to earlier parts of the current level