Here's my usual list (updated):
- Top priority:
Mechwarrior 2, 3, and 4 with all expansions (possibly #1 as well)
- High priority:
Mech Commander 1 & 2
Project IGI: I'm Going In
Prey (2006)
Tom Clancy's Splinter Cell: Pandora Tomorrow
Heavy Gear 2
Space Hulk 1 & 2
- Medium priority:
Cryostasis (hoping for a comeback)
Second Sight
Drakan: Order of the Flame
Oni
Alien vs Predator 2
Wolfenstein (2009)
- Low priority:
Future Cop: L.A.P.D.
Take no Prisoners
Laser Squad
Re-Volt (another re-release)
As usual, I'm not listing games such as Command & Conquer collection, HALO collection, Heretic and Hexen series, Max Payne series, WH40K: Space Marine, Rise of Nations, Deus Ex: Human Revolution and Mankind Divided, Dark Messiah of Might & Magic because they are available on other shops and so there's at least a way of acquiring them, although of course I'd much prefer to buy them on GOG.
Also: I have not included No One Lives Forever 1 & 2 because I have already played them in the past, but they definitely belong here!
Dray2k: Then there are so many Amiga and some C64 games out there that I want to see here.
Don't even get me started on that... there are so many titles I'd like to revisit, although I'm not sure it would work for GOG to start selling them.