Thanks to suggestion of @keeveek, please find below the list of The Winter Sale offers added on December, 13th. Every day I'll put in the thread the list of newly added offers.

Prices in EUR, but games are sorted by discount, which should be applicable regardless of your currency and regional pricing. The source of the data is my beloved Isthereanydeal.com.

New single deals:
• 2.19€ [-90.0%] - We Are the Dwarves!
• 1.69€ [-80.0%] - Anomaly Warzone Earth
• 1.69€ [-80.0%] - Anomaly Defenders
• 2.59€ [-80.0%] - Anomaly 2
• 0.89€ [-79.0%] - Anomaly Korea
• 0.89€ [-79.0%] - Anomaly Warzone Earth Mobile Campaign
• 1.29€ [-75.0%] - Anvil of Dawn
• 1.29€ [-75.0%] - King of Dragon Pass
• 3.79€ [-75.0%] - The Swindle
• 4.29€ [-75.0%] - Avernum 2: Crystal Souls
• 2.19€ [-74.0%] - Avernum: Escape From the Pit
• 2.19€ [-74.0%] - Tomb Raider VI: The Angel of Darkness
• 2.19€ [-74.0%] - Tomb Raider: The Last Revelation + Chronicles
• 2.19€ [-74.0%] - Medal of Honor Pacific Assault
• 2.89€ [-66.0%] - Tom Clancy's Rainbow Six
• 2.89€ [-66.0%] - Tom Clancy's Ghost Recon
• 5.79€ [-66.0%] - LEGO Harry Potter: Years 5-7
• 5.79€ [-66.0%] - LEGO Harry Potter: Years 1-4
• 6.79€ [-66.0%] - LEGO Batman 2: DC Super Heroes
• 4.39€ [-65.0%] - LEGO Batman: The Videogame
• 4.49€ [-65.0%] - Tempest
• 3.39€ [-60.0%] - Stunt Island
• 7.99€ [-60.0%] - The Banner Saga 2
• 2.59€ [-49.0%] - Wasteland 1 - The Original Classic
• 4.29€ [-49.0%] - Prince of Persia: Warrior Within
• 4.29€ [-49.0%] - Prince of Persia
• 4.29€ [-49.0%] - Bard's Tale, The
• 4.29€ [-49.0%] - Prince of Persia: The Two Thrones
• 2.79€ [-45.0%] - Fantasy Wars
• 16.19€ [-40.0%] - Brigador: Up-Armored Deluxe
• 3.29€ [-35.0%] - Gabriel Knight 3: Blood of the Sacred, Blood of the Damned
• 20.09€ [-33.0%] - Ken Folletts The Pillars of the Earth - Season Pass
• 4.09€ [-20.0%] - Gabriel Knight 2: The Beast Within
• 9.59€ [-20.0%] - Tower 57
• 25.19€ [-10.0%] - A Hat in Time

New bundles added on December 13th:
•Anomaly Bundle
• Lego Bundle
• Prince of Persia Bundle
• Tom Clancy Bundle
• Activision Variety Pack (still hidden at the moment)

It's been a long time since I've seen a thread recording the titles on sale. Thank you for taking the mantle. +1

Could you also add the new bundles? For example the Lego titles can also be bought together for a completion bonus.

Thanks a lot for your work!

GOG should start paying you for their work, thanks!

Please don't erase the older updates. And include the bundles :)

Definitely needed and much appreciated.

Thanks.

Thanks for this, just of note they are updating the sale around 3pm CET everyday.

I've already told them - I don't need money, just give me access to your database to get the data easier (: First comment has been updated.
The problem with bundles is that I don't have any tool to track them. The ones above I recognized as added recently thanks to this post of eiii (thanks, mate!).

Freedom Force, X-COM and Army Men games got 75% discount.

I'll add a new post and probably put all links in the first post.
Regarding bundles - please, find the answer above; someone need to let me know! I won't be able to update before 6pm CET. I need to get home from work :D Unfortunately, GOG is not the one who pay me ;)

You might want to mention the hidden Activision Variety Pack bundle as well since GOG still isn't showing it on the front page:
https://www.gog.com/forum/general/the_winter_sale_begins_grim_fandango_goes_free_c477e/post283.

thank you for this, frankly I give up trying to figure out what is newly placed with ongoing sales, the front page is way too cluttered, busy and gives me a headache.

thanks to this I just got dwarves for 90% off, cant beat that. cheers mate

This was sorely needed, and you have my gratitude for taking this on.

Still, it boggles my mind that the official alternative is to rummage through the front page for stars. Nothing against hidden object games, but I'd rather play one after shopping. There's no good reason for GOG not to do what you've stepped up to do.

I spotted last chance offer - Crookz - The Big Heist and UFO: Aftermath...

so, what's new today?