9 Jun 2019
75% off $3.79 A Golden Wake
75% off $3.79 Blackwell Bundle
75% off $2.49 Gemini Rue
75% off $2.49 Primordia
75% off $2.49 Resonance
75% off $3.79 Shardlight

10 Jun 2019
80% off $2.99 Geneforge Saga
74% off $1.29 Shivah, The
55% off $4.49 STASIS
75% off $3.79 Technobabylon
75% off $3.79 Blackwell Epiphany
25% off $11.19 Unavowed

Flash Deals
11-06-2019

Avadon 2: The Corruption - $1.99 [80% off]
Avadon: The Black Fortress - $1.99 [80% off]
Butcher - $3.99 [60% off]
Conga Master - $1.99 [80% off]
Kromaia - $3.99 [80% off]
Lumo - $3.99 [80% off]

12 Jun 2019
50% off $4.99 Jazz Jackrabbit 2 Collection
50% off $4.99 Jazz Jackrabbit Collection
25% off $11.19 Lorelai
35% off $16.19 Megaquarium
50% off $9.99 Where The Water Tastes Like Wine
55% off $6.79 Yono and the Celestial Elephants

13 Jun 2019
60% off $7.99 ABZÛ
54% off $2.29 Devil Daggers
50% off $4.99 Semblance
80% off $1.99 The Cat Lady
60% off $7.99 Victor Vran
75% off $3.79 Wuppo

6 Aug 2019
https://www.gog.com/promo/20190806_promo_launch_age_of_wonders
80% off $1.19 Age of Wonders
75% off $2.49 Age of Wonders 2: The Wizard's Throne
75% off $7.49 Age of Wonders 3
75% off $8.74 Age of Wonders 3 Deluxe Edition
50% off $3.49 Age of Wonders 3 - Deluxe Edition Upgrade
50% off $9.99 Age of Wonders 3 - Eternal Lords
50% off $5.99 Age of Wonders 3 - Golden Realms

7 Oct 2019
https://www.gog.com/promo/20191007_promo_launch_armikrog
70% off $2.99 Armikrog
70% off $4.49 Armikrog - Deluxe Edition

Flash Deals

For 8 hours until 22:00 UTC

Anno 1404: Gold Edition
$1.49 [90% off]
New best historical price

Anno 1503 A.D.
$0.59 [90% off]
New best historical price

Anno 1602 A.D.
$0.99 [90% off]
New best historical price

Anno 1701 A.D.
$1.29 [90% off]
New best historical price

Heroes of Might and Magic®
$0.99 [90% off]
New best historical price

Heroes of Might and Magic® 2: Gold
$0.99 [90% off]
New best historical price

Heroes of Might and Magic® 3: Complete
$0.99 [90% off]
New best historical price

Heroes of Might and Magic® 4: Complete
$0.99 [90% off]
New best historical price

Heroes of Might and Magic® 5: Bundle
$1.99 [90% off]
New best historical price

Dying Light: The Following – Enhanced Edition
$14.99 [75% off]
New best historical price

Braid
$3.79 [75% off]
Not the best historical price

The Witness
$9.99 [75% off]
Matches the best historical price

Flash Deals

For 10 hours until 24:00 UTC, 28th Nov.

The Curse of Monkey Island™
$2.09 [70% off]
New best historical price

Call of Juarez: Gunslinger
$5.29 [65% off]
New best historical price

For 12 hours until 02:00 UTC, 29th Nov.

Druidstone: The Secret of the Menhir Forest
$9.99 [60% off]
New best historical price

Pathfinder: Kingmaker - Imperial Edition Bundle
$37.59 [53% off]
New best historical price

Kingdom Come: Deliverance Royal Edition
$19.99 [50% off]
New best historical price

Minoria
$9.99 [50% off]
New best historical price

Dry Drowning
$10.99 [45% off]
New best historical price

For 14 hours until 04:00 UTC, 29th Nov.

Pathologic 2
$20.99 [40% off]
New best historical price

Apsulov: End of Gods
$13.99 [30% off]
New best historical price

Jenny LeClue - Detectivu
$13.99 [30% off]
New best historical price

7 Dec 2019
30% off $17.49 Valfaris
30% off $25.12 Valfaris Digital Deluxe Edition

13 Dec 2019
20% off $31.99 Disco Elysium

6 Mar 2020
95% off $1.24 We are the Dwarves

8 Mar 2020
91% off $2.24 We are the Dwarves

However, the countdown clock is slightly larger than one single day.
So it is not really a daily deal.

1 Nov 2020
60% off $9.99 Owlboy
60% off $11.99 Owlboy Collector's Edition

Was this an actually a daily deal? Because it looks like I missed it.

I tried to buy a game on STEAM, for whatever reason their checkout didn't work for the last 2 hours of the Halloween sale, so I missed that. I bought by mistake the first Telltale Batman game, instead of the collection with both games, I asked for a refund, still haven't heard from GOG support. Now this... WTF is happening...

EDIT: I typed this twice because GOG 's forum ate my first post. :(