Quoting Marcus Fenix from Gears of War - I don't think I can count that high.
That's how many of them are there.
Even digging for hour in my old libraries would bring, at best 1/3 of them.

Anyway - on top of my head:

Myth trilogy
NOLF 1and2
Gears of War saga
Cold Zero
Demise - Revelation (and Mordor)
Devil Whiskey
Knights of the Chalice
Pyl
Książę i Tchórz (Prince and the Coward)
Original War
Diggles
Devil Inside

and Polish version for already released games here - DungKeeper2, Gorky17...most translatedy by CD Project, GOG is CD Project (sort of?) and still - translations are not there

Just about anything from Mircosoft's catalog. I think they may be last major name with no presence on GoG. Freelance, Age of Mythology, and Fable are three that come to mind that I'd really like to see.

Imagine all those reactions coming from the triggered leftists if Gog introduced Hatred . You can do it Gog, I am counting on you. :-)

All of the Pong Kombat games, and Smashing Pumpkins Into Small Piles of Putrid Debris.

I'd love to see Second Sight rereleased.

Yo! All of Mike Hommel's older games are freeware now :) - https://hamumu.itch.io/spispopd

I've long given up the hope of ever seeing Battlefield 1942, Battlefield Vietnam and Battlefield 2 here. EA games has buried even the memory of it, it seems.

Would be nice if they could bundle that as a bonus extra with DOOM. :)

That'd be fun. If you do try it out, let me know if you're able to get it running with DOSBox.

Quite a lot, i just mention the most important ones I want to see here.

Sim Copter, Diablo 2 with its Add-On and Knights of Honor are games I really want to see on here. Probably the most paramount. They're just very GOG-core games.

Besides that, the game I personally want the most on here is Comanche.

Then there are so many Amiga and some C64 games out there that I want to see here. Games such as Uridium 2 and what is probably the best convention of Rainbow Island and Turricane for the Amiga in existence. Theres also Moonstone and GODS for the Amiga, games that were pretty fun on the machine but also pretty much GOG-core retro games. The C64 also had some good arcade conventions, stuff like Bubble Bobble for instance. But I also would like to see games like Lazy Jones on here. At any case, some of these games should be aquireable somehow.

There is also a rather unknown game called Z.A.R. (old PC games based around the tech that made voxel games like Comanche possible) and Blade Warrior (A Amiga game with a unique art style), both are available on Steam but not here, which is a huge shame.

Add to this list:
Samurai Shodown (2019)
Soul Calibur VI
Tekken 7
Spyro - Reignited Trilogy
Mortal Kombat 11

And if it ever gets ported to a PC, Crash Team Racing Nitro-Fueled would be a nice addition.

DROIDWORKS!!!

Also, Age of Empires 1 & 2

Man, I've got loads of games that I'd love to see on GOG... It's hard to just pick a few. But here's some:

The A.I.M. series
ANY Mechwarrior or Battletech game
Dues Ex 3 & Mankind Divided
Anything from the Earth Siege or Star Siege series
Freelancer
The How to Survive series
The Lost Planet series
Perimeter 2
The Outer Worlds

Some of those games we might well see here one day. But some of them you can't even get anywhere because they've functionally abandomware due to their parent companies having gone out of business or they're owned by companies that just don't care to releases them.

I'm not sure what the holdup is on Knights of Honor, it's published by Paradox on Steam and they've been decent about bringing some games here.

I would have thought that is already here because the earlier games in the series were, but apparently not.

At least it is not about DRM or copy protection, as I already got that game years ago with the Strategy First SFI Super Bundle offer IIRC. It is a digital DRM-free installer, pretty much like GOG games.

Other games:

I still can't understand why Crysis 2 is not already here. Did they just forget to release it right after the earlier Crysis games?

While Bethesda is on its GOG release streak, yeah Skyrim would be nice. I'd be glad with the older Skyrim (Legendary Edition, which includes the DLCs).