Any of the old AD&D games like the goldbox series or
Ravenloft: Strahd's Possession and
Ravenloft: Stone Prophet
Fantasy Empires
Master of Orion II
Psychonauts
Imperialism
X-COM: UFO Defense/UFO: Enemy Unknown
X-COM: Terror from the Deep
Lords of Magic: Special Edition
Populous II
Syndicate
Syndicate Wars
Transport Tycoon Deluxe
Captive
Most probably mentioned before, but all worth re-mentioning ^^

Original Command and Conquer with all of Nyergud's mods, maps and missions included (from the PS1 and N64 versions etc) in the install.
Also now that I've read someone else's comment re: emulation -
the Front Mission series. Maybe Sega's Virtual On as well - that had a pc version but I forget how good it was compared to the arcade one.

These are already available for free (from fileplanet at least). It would be nice to have on GOG though.
They've already been said, but I'd love to see Master of Orion II, Sid Meier's Alpha Centauri, and Little Big Adventure 1 & 2.

Dreamweb.
Listening to the OST of this game still gives me the shivers.. While playing this game I experienced something that left me silently contemplating it's message for days on end.. It would make me really happy to see Dreamweb revitalized, playable on modern operating systems. It's a gem which will always warm my heart.
Thank you, GoG.

Games with problems on XP:
Soulbringer
Blood 2
Requiem Avenging angel
Thank you

Yes, that is a great game!

Time, lots of time- to play all of the above!!

Growing up in the 90's and playing games on my dads Mac, my favorite games were Descent (already on GOG, yay) Lode Runner 2, and X-Wing. X-Wing still ranks as one of my favorite games of all time. I have the disc, but no computer that will run it.
PLEASE can we get X-Wing (and maybe Tie Fighter)?

Oh, oh, and the absolutely stunning 1995 PC-CD version of Mike Singleton's Lords of Midnight would be quite nice too. It was released by Domark if I remember correctly.

Would love to see Realms of the Haunting on here. Metal Gear Solid is another good one.

Hi guys, first post here :)
I'd personally love to see:
Thief: The Dark Project (Gold edition if possible)
Thief II: The Metal Age
And this one may be a tad too old but...
Crusader No Remorse
:)

Blood 2, Mafia...but I would like to see more game series here, to be able to enjoy from the old times until recent releases...like Max Payne series, Quake series, Soldier of Fortune series, Duke Nukem series (incl. Forever :)), GTA series, ST: Elite Force series...

We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood! We want Blood!

Oni

Heart of Darkness and Pandemonium Series would be great addition.