Don't know Steam schedule, but here are Monday (Weekly), Wednesday (Midweek) and Friday (Weekend), starting 12:00 Polish time.

Thank you.

20190204 | Weekly Sale | Picks for the picky

• $ 1.19 • -80% • I Have No Mouth And I Must Scream
• $ 1.19 • -80% • Metal Fatigue
• $ 1.19 • -80% • Space Rogue Classic
• $ 1.19 • -80% • Terra Nova: Strike Force Centauri
• $ 1.19 • -80% • Timelapse
• $ 1.19 • -80% • Titanic: Adventure Out of Time
• $ 1.49 • -75% • Bad Mojo Redux
• $ 1.49 • -75% • D: The Game
• $ 1.99 • -80% • Feist
• $ 1.99 • -80% • Noctropolis
• $ 1.99 • -80% • System Shock 2
• $ 1.99 • -80% • System Shock: Enhanced Edition
• $ 2.39 • -59% • Tropico Reloaded
• $ 2.49 • -75% • The Original Strife: Veteran Edition
• $ 4.49 • -70% • Tropico 3 Gold Edition
• $ 4.99 • -75% • Shadowrun Hong Kong - Extended Edition
• $ 4.99 • -75% • Turok
• $ 5.99 • -60% • Tropico 4
• $ 7.49 • -75% • Necropolis: Brutal Edition
• $ 7.49 • -75% • Shadowrun Hong Kong - Extended Edition Deluxe
• $ 9.74 • -35% • Freedom Planet
• $ 9.99 • -50% • Turok 2: Seeds of Evil
• $14.99 • -25% • Forsaken Remastered
• $14.99 • -40% • Tropico 5
• $16.24 • -35% • SUPERHOT
• $16.99 • -15% • Battle Princess Madelyn
• $20.99 • -40% • Tropico 5: Complete Collection
• $23.99 • -40% • BATTLETECH
• $24.99 • -50% • BATTLETECH - Digital Deluxe Edition
• $71.99 • -20% • BATTLETECH - Mercenary Collection

Aw shoot, missed Kholat! Thanks for posting, though.

20190206 | Midweek Sale

• $0.74 • -85% • Valhalla Hills: Two-Horned Helmet Edition Upgrade
• $1.49 • -75% • Celtic Kings: Rage of War
• $1.49 • -75% • Cossacks Anthology
• $1.49 • -75% • Imperium Galactica
• $1.49 • -75% • Tzar: The Burden of the Crown
• $1.49 • -90% • Ultimate General: Gettysburg
• $1.99 • -80% • Caravan
• $1.99 • -80% • Heroes of Annihilated Empires
• $2.24 • -85% • Valhalla Hills
• $2.49 • -75% • Cossacks II Anthology
• $2.49 • -75% • Imperium Galactica II: Alliances
• $2.49 • -75% • SpellForce Platinum
• $2.49 • -75% • The Guild 2
• $2.49 • -75% • The Guild 2 Renaissance
• $2.49 • -75% • The Guild 2: Pirates of the European Seas
• $2.49 • -75% • The Guild Gold Edition
• $2.49 • -75% • Victoria Complete
• $2.49 • -75% • Zeus + Poseidon (Acropolis)
• $2.99 • -50% • Dark Reign 2
• $2.99 • -50% • Emperor: Rise of the Middle Kingdom
• $2.99 • -80% • Europa Universalis III Complete
• $2.99 • -85% • Valhalla Hills: Two-Horned Helmet Edition
• $3.74 • -75% • SKYHILL
• $3.74 • -75% • SpellForce 2: Faith in Destiny
• $4.79 • -20% • Caesar
• $4.79 • -20% • Caesar II
• $4.79 • -20% • Call to Power 2
• $4.79 • -20% • Conqueror A.D. 1086
• $4.99 • -50% • Dark Reign + Expansion
• $4.99 • -75% • Expeditions: Conquistador
• $4.99 • -50% • Pharaoh + Cleopatra
• $4.99 • -75% • SpellForce 2: Demons Of The Past
• $6.24 • -75% • Bounty Train
• $6.49 • -35% • Caesar IV
• $8.99 • -70% • Ultimate General: Civil War
• $9.89 • -67% • The Long Journey Home
• $14.99 • -50% • Expeditions: Viking
• $15.99 • -60% • Shadow Tactics: Blades of the Shogun
• $24.99 • -50% • SpellForce 3

Is Tzar complete?

20190208 | Weekend Sale

• $2.49 • -75% • Journey to the Center of the Earth
• $2.49 • -75% • Magrunner: Dark Pulse
• $2.49 • -75% • Sherlock Holmes versus Jack the Ripper
• $2.49 • -75% • Sherlock Holmes: Nemesis - Remastered
• $2.49 • -75% • Sherlock Holmes: Secret of the Silver Earring
• $2.49 • -75% • Sherlock Holmes: The Awakened - Remastered
• $2.49 • -75% • X: Gold
• $2.99 • -50% • Shogo: Mobile Armor Division
• $2.99 • -50% • X2: The Threat
• $4.99 • -50% • Battle Chess Special Edition
• $4.99 • -50% • Castles 1+2
• $4.99 • -50% • Conquest of the New World
• $4.99 • -50% • Cyberia
• $4.99 • -50% • Cyberia 2: Resurrection
• $4.99 • -50% • Descent
• $4.99 • -50% • Descent 2
• $4.99 • -50% • Descent 3 + Mercenary
• $4.99 • -50% • Descent: Freespace Battle Pack
• $4.99 • -50% • Die By The Sword + Limb From Limb
• $4.99 • -50% • Dragon Wars
• $4.99 • -50% • Earthworm Jim 1+2: The Whole Can 'O Worms
• $4.99 • -50% • Earthworm Jim 3D
• $4.99 • -50% • Evolva
• $4.99 • -50% • Freespace 2
• $4.99 • -50% • Giants: Citizen Kabuto
• $4.99 • -50% • Ignition
• $4.99 • -50% • Invictus: In the Shadow of Olympus
• $4.99 • -50% • Jagged Alliance 2: Unfinished Business
• $4.99 • -50% • Kingdom: The Far Reaches
• $4.99 • -50% • Kingpin: Life of Crime
• $4.99 • -50% • Lionheart: Legacy of the Crusader
• $4.99 • -50% • Lost Eden
• $4.99 • -50% • M.A.X. + M.A.X. 2
• $4.99 • -50% • MDK
• $4.99 • -50% • MDK 2
• $4.99 • -50% • Messiah
• $4.99 • -50% • Of Light and Darkness: The Prophecy
• $4.99 • -50% • Pray for Death
• $4.99 • -50% • Prehistorik 1+2
• $4.99 • -50% • Redneck Rampage Collection
• $4.99 • -50% • Sacrifice
• $4.99 • -50% • Screamer
• $4.99 • -50% • Screamer 2
• $4.99 • -50% • Shattered Steel
• $4.99 • -50% • Star Trek: 25th Anniversary
• $4.99 • -50% • Star Trek: Judgment Rites
• $4.99 • -50% • Star Trek: Starfleet Academy
• $4.99 • -50% • Star Trek: Starfleet Command Gold Edition
• $4.99 • -50% • Stonekeep
• $4.99 • -50% • Subwar 2050 Complete
• $4.99 • -75% • The Testament of Sherlock Holmes
• $4.99 • -50% • Titus The Fox: To Marrakech and Back
• $4.99 • -50% • Toonstruck
• $4.99 • -50% • VR Soccer '96
• $4.99 • -50% • X3: Reunion
• $6.79 • -66% • X Rebirth: Home of Light Complete Edition Upgrade
• $6.79 • -66% • X3: Terran War Pack
• $8.99 • -70% • X Rebirth
• $16.99 • -66% • X Rebirth: Home of Light Complete Edition
• $44.99 • -10% • X4: Foundations
• $71.99 • -10% • X4: Foundations Collector's Edition

Tremendous effort, ciemnogrodzianin! Thank you for the "public service" you are providing.

I'm happy that you find it useful!

Most of kudos to tireless Python script (I learned a lot working on it, which makes me even more happy;). If you think that some additional information would be useful or something should be changed, let me know, I'll check if it's possible.

Have a nice weekend, Gede!

Depends on your definition of complete :-)
I mean I think that it is complete, but in some countries there were additional campaigns and these campaigns are not included.

If you want more information you can go here:
https://www.gog.com/forum/tzar_the_burden_of_the_crown/download_expansion_campaigns_officially_released_only_in_spain_and_italy/post1

Thank you

Ha, aggregating is on my to-do list for a while, but to be honest, I have no idea how to achieve that properly. The sales reported here are just the tip of the iceberg. There is a lot of smaller sales and deals. Kbnrylaec makes great job tracking them here.

As I understand the challenge, to make a proper database I should:
a) collect full data of GOG catalogue,
b) crawl over all games at least once a day to collect info about current discounts,
c) store the data in some reasonable form - which means, I suppose, database structure containg at least dimention table for games' details and some facts table containg discounts data,
d) to make it automatic, it should be placed somewhere on a server.
The effect would be valuable for sure, but it would also be nothing more than current data avialable in RWareHall's spreadsheet (much better accuracy), IsThereAnyDeal and GogDb. And it would take years to build a reasonable historical perspective. All above makes me avoid the task :)

However I'm storing, indeed, data for Weekly/Midweek/Weekend sales and this kind of summary is good idea, I think. However it will never be complete view. Only RWareHall knows everything :)

It seems to me that you are over-engineering things. No need for a database, a simple CSV file (or a simple pickle file) is sufficient to store the data. Then you can use collections.Counter() to add up the entries.

There is no need to reinvent the wheel since, as you said, there are other people doing the "large scale" collecting. But it does give you a new objective to reach for.
Have fun!

The database is the easy part ;) At least - it simplifies a lot. Pickles may be fine, but even now, after one year there is ~150 lists of discounted games for each of 3 sales started every week, so storing the data in well-designed tables makes it easier to maintain in the long run. IMO the problem is that every-day full-scan on GOG library is needed to get a proper prices of all titles in all promos. But I'll think at some simplified formula - perhaps just catching and keeping the historical low and date or something may be a nice comprimise.
Thanks for ideas!