Maybe Act of War wasn't only stalled technically, but also legally (remember, Atari went through a bankruptcy that might have prevented any further deals till they became a stable company again). Besides, they also released the 2 Call of Cthulhu games later, so it seems that they have started becoming more active again.

As for Square Enix, I remember hearing that GOG had plans for Gex 3D and they were also trying to gauge interest for the new Thief.

What would it take to get Nintendo and Sony exclusives here?

An unholy ritual requiring live human sacrifices.

http://www.gizmodo.com.au/2015/03/nintendo-games-officially-coming-to-pc-mobile/

Yes, yes, I know about that. I want to see what they release and not just the possibilities. For all we know, it might be nothing more than companion apps to their normal games.

It's pretty unlikely to happen but I'd like to see here games from systems other than PC, especially from the 8 and 16-bits era and from both consoles and computers (yes, we have some lonely Amiga title): C64, Spectrum, NES, Genesis, etc.

Chuck Yeager's Air Combat.

Aces Over Europe
Aces Over the Pacific

Jane's AH-64D Longbow

Everything Steel Panther

Emulated Amiga's Neuromancer (or C-64 without the disk wait), not the crappy looking and sounding PC version.

Command & Conquer Generals & Renegade
Delta Force Land Warrior

We'd have to abduct the princess and hide her in a series of castles...

As things stand, nothing short of a miracle. If you want an inside look at Sony's corporate culture and their stances on piracy and DRM, search the WikiLeaks archive on those topics, and you'll see they are heavily invested in developing and selling DRM "solutions" and making piracy look more costly than even they admit:
https://wikileaks.org/sony/emails/emailid/114796

Maybe the wrong URL? That one appears to be an e-mail about how Sony is supposed to refer to Taiwan, not about DRM. But that is actually an interesting e-mail, too.

The games I would pick are Portal, Portal 2, and Bloodlines.

Amiga versions of all the games already in the catalogue from the time period when they were generally superior to the PC version in in some way or the other. Unlikely because of hard-to solve licence issues in Amiga emulation.

While there are ways to solve these issues - easiest is to buy Amiga Forever - GOG probably also doesn't want to release games in a state where you need to buy additional components elsewhere to run them. But there is some hope ever since Cinemaware showed it can be done. While the excitement surrounding that went sour quick, they have been promising a surprise for us towards the latter part of the year, so who knows...

Other than that I'd really love a DRM-free Assassin's Creed: Brotherhood with a functional multiplayer. I guess I could accept Galaxy for that. But this won't happen.

All three discworld games.

Warcraft 1,2,3
Starcraft 1 + addon
Dune 2000
Emperor: Battle for Dune
Paraworld
Armies of Exigo
Star Trek Armada 1+2
Diablo series
Delta Force games
Amplitude Studios games - Endless Space, Endless Legend
Stardock games: Sins of a Solar Empires Rebellion, Fallen Enchantress, Sorcerer King, Ashes of Singularity
Planetary Annihilation
Creeper World series
Railroad Tycoon
Sword of the Stars and tons more.

Command and Conquer: The First Decade! And NOT the rest, the ultimate collection, for two reasons mostly: 1) TFD has community patch and support. 2) Later, non-westwood games, are REALLY cr@p...

Diablo 1 + Hellfire and Diablo 2 + LOD. I got them retail, TWICE. So much i loved them. I would buy them here a third and final, or maybe not final, time, without a second's pause to think.

Vampire Bloodlines. Copyrights' hell and real mess, total chaos. Would buy it even at full price of day 1 release, here. The most flawed masterpiece of a game ever produced.

Sid Meier's Pirates 2004 Remake. For some obscure reason, it seems it is never going to grace our corner here... What a pity...

Titan Quest. For some obscure reason too, it seems it is never going to grace our corner here, either... What a pity, too...

GTA series. 150% unlikely, but hell, i would buy them again, here. Especially now that they have stopped gifting out 1 and 2, from their classics webpage.

The Suffering collection. Those are excellent good old games and they have aged exceptionally well! Why they aren't here already, is one of those huge mysteries of mankind and all.

FEAR 3? Just to complete the collection? Not that it was a good FEAR, no, a good game basically, but oh well...

Naruto series! I hate to still keep steam around, just so i can play this... 3 was great, revolution was filler and cr@p, 4 is going to be great. Hey, Namco Bandai is still a pal, even if it "stole" from you guys two millions and sued you for removing DRM from witcher 2, right?

Warcraft 2 + Beyond the Dark Portal. I absolutely want to see and play this HERE, before i can rest in peace.