I vaguely remember GEM in MS-DOS because it was the only software I knew of (iirc) that supported the mouse we had. One of those early optical mice with a metal mousepad with a grid of tiny reflective dots. No one else I knew that had a PC had a mouse back then.

It also had graphics programs. One for bitmaps and one for vectors, iirc. Me and my friend used to play with those. I don't even remember what else GEM was for. To me it was just a way to launch those editors to draw things and I did not have access to any other graphics applications in DOS until years later.