Lemmings, Commander Keen, Secret Agent: The Hunt for the Red Rock Rover(not a particularly good or notable game, but it comes to mind somehow), Cosmo's Cosmic Adventure, SimCity 2000, Catacomb Abyss, Chex Quest...
Oh and also a bunch of edutainment. Oregon Trail II and Gizmos and Gadgets.
I know you said gaming memory (singular), but as far as chronology goes I can't remember what the first was.