More competitor than simply related. At least on the PC front.
Was something I aspired to acquire, but never did.
Just running real-mode Win 3.1 in a window was a pretty awesome feat.
Yeah, apart from that. "Other than that, how did you enjoy the play, Mrs. Lincoln?" As if someone interested in the history of such interfaces can even put that one into proper context without considering contemporary developments.
"Related" can be used two different ways:
[1] This software is related to that software -- as in, they shared code, or a design, or something. PC GEM is related to Atari ST GEM; PC GEOS is related to C64 GEOS.
[2] software A is relevant to software B, and if one is considering A one should also know about B.
I think which is meant here is clear.