OST : https://www.youtube.com/watch?v=8PyTKOD-
u2Y

Note  : Normally Part 1 is played 1 octave up ( the 2nd 
time ) but I simplified to a repeating,
        Part 3 isn't accurate coz I just understood nothing 
there, & Part 4 is detuned to be playable

Bonus : Here's Mini Tutorial about: 
       
          How to build an ATARI ST arr. 

1. u need a rom of the game, use google to find it ;-)

2. u need Saint emulator
[http://leonard.oxg.free.fr/SainT/saint.html]
to create a chiptune file, lauch the game , then YM 
record ON when music start, don't forget record OFF , 
u just ripped it -(^_^)-

3. Now u need a player called STSOUND
[http://leonard.oxg.free.fr/download/stsound.zip]
If you are lucky the melody track & bass track are 
separate, so u can hear it separatly, select channel A, 
B, & C ON/OFF as u wish  ^^

Alternativly STSOUND can also create a Wav file , it's 
usefull to play it in a music player including 
looper/slower/detuner functions as AIMP or  
RiffMaster Pro  [http://www.aimp.ru/index.php?
do=download]

4. Finally the best part, wrote note after note by 
ear ^^  ofc a music editor can help a lot : Guitar pro 5, 
Tuxguitar
[http://tuxguitar.herac.com.ar/download.html]