I was just perusing this issue recently for kicks and giggles. I’d forgotten it was the precursor to Marvel’s Contest of Champions, which, in turn, was the precursor for the original Secret Wars and then, again, the recent Secret War that revamped the entire Marvel Universe.
Thus, GSD#3 is one of the most important comics in history!
Written by the great Steve Gerber, along with Jim Starlin and Len Wein, illustrated by Starlin, and colored by Len’s wife, Glynis, the story is basically Grandmaster (the big blue guy) playing against Prime Mover, and using various superheroes from Earths one and two as gamepieces. The story is just the engine to drive big superhero battles. But it’s awesome.