Not the earliest games i remember playing but here are a few that stand out. Playing on the ol' 286! 64k ram baby!
The origional Test Drive
Stunts (They have to make another updated version of this)
Commander Keen, Chuck Yagers Air Combat, Battle Chess, Kings Quest, Police Quest, Space Quest, first Simcity, Golden Axe, Heretic, Magic Carpet (mind blowing), One Must Fall, Street Rod, Wing Commander, Tank Wars and more.
QBASIC Gorillas