I started gaming on PC with Doom and the 2D Dos games.
Here are my favorite in no order
Decent Free Space 1,2 and expansions (my favorite)
Commander Keen series
Crystal Caves (must play that again...)
Need For Speed SE
Awe the memories. I've tried playing Decent 1 again, but the graphics are horrible. I must have had a better imagination when I was younger.
That or you were using a much smaller monitor so the graphics looked better -- Decent always made me dizzy ! (not that that stopped me from playing it!) -- I still miss the old Infocom Text based games like the Zork trilogy, Deadline, etc.