Oh, how great it would be if GOG could sign up with Microsoft! Could it be Freelancer? Or AoE? Or, dare I say, Urban Assault? :P

Dungeons II, woo!
*please be Dungeons II next :P *

I'm guessing since it's "quite the surprise" it'll be a new publisher signing. But seriously, GOG, do not play with my emotions like this:

Wow, if GOG truly got Bethesda/Zeni, that could mean... id Software games!

I hate you SOOOOO much ;) But I eagerly await the tease. I hope it's this coming week, as my poor continence can only take so much!

Wait, was that entry there before? If this is new, then wow, this "surprise" is going to be interesting.

I still don't understand why the Company/Publishers list isn't in alphabetical order...

Quite a surprise?

I think we'll get some new games by an old publisher. My guess is Thief (2014).

Also listed:

id Software
Konami
Namco Bandai

Kiddo, then you're at the wrong place. These guys get P-A-I-D to "cuckoo-cuckoo" with ya, bud :P

I'll head off my guess with Star Trek games. If that's not the case, then Star Wars. Barring those 2, it's gotta be a publisher.
However, given the suprise is soon-ish with no spoilers, I'd probably guess it's a major publisher with many must-have games

I'm thinking Strategic Simulations Inc. games.

https://en.wikipedia.org/wiki/List_of_Strategic_Simulations,_Inc._games

I'm thinking the Gold Box series or Eye Of The Beholder trilogy.

After I saw this interview, my new guess is Wizardry 1-5. Or maybe the Eye of the Beholder series.

It's not a "game" pre se but a hey look Linux and Mac versions averrable for 10-20 titles at once kind of deal?

It's by number of entries. The companies that have the most games are listed first, the companies with the least are listed last. There also doesn't seem to be any deleting of entries, so if a company loses the rights to a game, it may remain in the list, even though it has 0 games.