Thanx to Brume we have now STX images of this rare game. And I finally did updated versions of full game with original title audio.
http://atari.8bitchip.info/ASTGA/G/ggs.php
Floppy version requires 512KB only, SS floppy. There will be fine scroll on machines with blitter.
Hard disk, TT, Falcon versions with fine scroll + level maps here:
http://atari.8bitchip.info/SCRSH/greatgs.html
That's awesome, thank you Peter / Brume :D
Steve