Will proceed to do so when I get confirmation about the 5 remaining games (ArmA Cold War, ArmA Gold Edition, SpellForce Platinum, SpellForce 2: Shadow Wars and SpellForce 2: Dragon Storm). I will also create a GOGmix to go along with this thread (said GOGmix won't be complete, though, because you can't list removed games on it).

Did a quick but thorough search, those are the titles I found that came with a key:

Arma 2 Combined Operations
Battle Worlds Kronos
DEFCON (This one should have an exclamation point added to the list, because it's pretty much unplayable unless you enter the serial key, even if you're playing against bots - the game will restrict you to one opponent only unless the serial key is entered. I'd say this one flat out disqualifies as a DRM-free game, IMHO.)
Din's Curse
Eador Masters Of The Broken World
Far Cry 2
Galactic Civilisations I UE
Heritage Of Kings The Settlers
Mount & Blade With Fire & Sword
Multiwinia
Neverwinter Nights 2 Complete
Race The Sun
Rise Of The Triad '13
Settlers 3
Settlers 2 10th Anniversary
Tales Of Maj'Eyal
Tropico 3
Two Worlds 2 Epic Edition
Unepic
Wargame European Escalation

Glad to see you're going to take care of the other thread! I hate to admit that I usually don't really check out retail copies any more.

A similar problem exists with Tropico 3. The default serial prevents the game from initializing (a bug with Windows 7 or something, apparently). You must then delete a configuration file and then the game will ask you for the serial, which you must input from your account.

You sure that the original version of Settlers 2 requires a serial? I haven't seen other people reporting this.

Please do. It would help with the list in those times that the vast majority of retail games have account-based DRM. If you aren't going to buy them, at least reporting them would be useful. By the way, you never told me if the retail edition of Hard Reset requires registration.

Sorry, typo. That's supposed to say Settlers 3. Settlers 2 is serial-free (at least the non-10th Anniversary version is).

That's because I never got around to installing it. :P
I'll try to check it out some time this week.

OK. Thanks for the clarification. I will be awaiting your input in the other thread. ;)

Defcon requires a serial number. It is supposed to populate automatically, but I had to manually change it to what was listed on my game shelf.

"Double Take". Does it still come with a serial in your account or you have just backed it up? I ask because it doesn't come with a serial in my account anymore.

Nope, the serial is not on my account any more either. Oh well, good thing I backed it up, should come in handy if I ever get to use the old installer. ;)

The UnEpic serial was there if you wanted to beta test the features on Steam. It was removed since those features have been tested and will be added to GOG soon-ish. Multiplayer build was sent to GOG a couple of days ago.

I requested multiplay keys from Support for all four Spellforce titles. Here's the email I got back:

Please save the attached file onto your computer, extract it, and run the appropriate .REG file (the one suited for your operating system: 32 or 64 bit), by double-clicking it.
This file will modify your system registry, and apply the serial key.

Attached to the email are two ZIP files, one named SpellforcePlatinum_64bit_[my]_[email]_com.zip, and one named Spellforce2_SW_32bit_[my]_[email]_com.zip. In spite of the names, each ZIP contains both 32-bit and 64-bit registry files. The bracketed parts of the name are redacted, they actually correspond to my email address as [my]@[email].com.

I need some more clarification from you:

1) How exactly did you request them? The current multiplayer key request form is not available for removed games.
2) For which games did you receive the serials? Given the filenames, I would have to assume for SpellForce Platinum and SpellForce 2: Shadow Wars.

Support
Contact Us
Select type of your inquiry: Other (general feedback, suggestions, kudos... etc)
Problem type: multiplayer key request

In the title I put "Spellforce multiplayer keys", and in the body I listed all four titles and requested the multiplayer keys for them.

Yes, I believe those are the games the keys belong to.

Thank you for the info! Time to update the list.

So you requested the serials after the games had been removed? I know it seems obvious but I want to be 100% sure. :)

Yes, I requested the keys yesterday. :)