In fact, alongside BioShock and BioShock 2 Remastered, GOG.com's Winter Sale has some 1900+ deals with same games available at 90% off. Other major titles with significant savings as part of the Winter Sale include The Witcher III: Wild Hunt Game of the Year Edition (60% off), Thronebreaker: The Witcher Tales (20% off), Divinity II: Original Sin Definitive Edition (35% off) and Hellblade: Senua's Sacrifice (50% off) among much, much more.

Here's what GOG.com shared with us officially:

BioShock™ and BioShock 2™ emerge from somewhere beyond the sea, dripping with that claustrophobic atmosphere of decay, corruption, and human ambition gone wrong.
Widely considered as the gold standard for story-driven shooters with light RPG elements, they have been remastered to feature higher resolution textures and models, director's commentary, and several other additions that ensure time will never wash them away.

Both games are joining the Winter Sale line-up with a 75% discount until January 3. And while we’re on the topic of big savings, there are +1900 games on sale including …

Don’t miss Daily Deals - the best offers you can find available for 24 hours only. Check back at 2:00 PM UTC every day for eight new games you won’t otherwise find in Winter Sale.

Unlock free games while you shop in the sale: get Fantasy General free with your first purchase, and EVERSPACE once all your Winter Sale spendings add up to $15.

Note: BioShock™ and BioShock 2™ on GOG.COM are available in Remastered versions. The original ones will be added as a free bonus at a later date.