GOG used to give away games that interested me but after the 3rd or 4th indie game I knew I would never play I stopped and only grab games that I know I want.
GOG
Duke3D
Prefer my original disc and have finished many times
Bio Menace
Only got for Nostalgic value, Never really liked the game. If I was going to play it, If was going to play I would do so on a real dos rig.
Total Annihilation
I want to like this game but I just can't get into it. I would play the GOG version though as don't own any other copy.
Dungeon Keeper
Prefer my original disc finished a few times
Hitman: Absolution
The Hitman series looks interesting but haven't started and doubt I ever will.
Epic
GTA V
May start after I finish the original GTA SA but not high on my list.
EA/Origin
Simcity 2000
Prefer my original disc, I guess I've spent enough hours to call it finished for a game with no end