The cards themselves were included as Feelies for the Hearts of Stone DLC (Monsters and Scoia'Tael decks) and sold at CD Projekt booths during gaming conventions in Poland (Northerners and Nilfgaard decks).
Friendship on the Set: Anya Chalotra (Yennefer) and Joey Batey (Jaskier) describe themselves as best friends both on and off the set, having grown very close during filming. They frequently give interviews together and have a lot of fun.
No Export for You: Zig-Zagged. For a while, the novels were not available outside of Poland, the Czech Republic, and a few central European countries (and the further you got from those nations? The more and more obscure they became). The success of the video games was what caused this trope to be averted... but predominately for European markets and in English speaking countries. For those in Latin America, The Witcher remained fairly obscure until the 2019 series.
Word of Saint Paul: It is generally accepted among the fandom that Korin from Road of no Return was Geralt's biological father. However, it was not Sapkowski who came up with this idea, but rather Maciej Parowski, writer of the comic book adaptation.
Word of Dante: Since the author has a rather Shrug of God-style attitude, many world-building details were filled out by the fandom, the tabletop game, and finally the video games. The world map is probably the best example, as no map has ever been included in the novels. Even then it's just one of several versions circulating in the fandom. Meanwhile, the tabletop game has the honor of naming the narrower setting as "the Continent".
What Could Have Been: Then pre-production for the The Hexer started, Andrzej Sapkowski was offered to simply pen the script himself or at least work with Michał Szczerbic (who was attached to the project from the start). He refused on a very simple grounds: when he was approached about it, he just finished writing Baptism of Fire and was on a tight schedule to finish rest of the saga, with remaining two books ahead of him. Then his relationship with the production execs soured before he even finished writing the saga and ultimately set him against the adaptation. Not only this greatly affected the final result, creating both production problems and affecting quality of the series due to copyright shinenigans, but, more importantly, permanently affected Sapkowski's perception toward just about anyone trying to adopt his works or use them for anything. His dismissive attitude toward the plans of the first video game (and then bitter resentment of their success) can be traced all the way back to that, just like the Flip-Flop of God attitude toward any adaptation. All because he was approached too early about prospect of working as a script writer.
Fan Translation: Made long before the series was fully published in English. Also the only way to read Droga, z której się nie wraca (Road of No Return) and Coś się kończy, coś się zaczyna (Something Ends, Something Begins) in English.
This was also the only way to read the books in Spanish... which unfortunately was much much harder to obtain.
Money, Dear Boy: After years of constant claiming that he would never return to Witcher, that he considered it his worst creation and practically burning all the bridges, Andrzej Sapkowski, the author, published Season of Storms, calling the saga his biggest achievement and best idea ever. To his credit, he openly admits this trope.
Disowned Adaptation: Zig-Zagged. Sapkowski stated that while he respectsCD Projekt RED's storytelling abilities, he does not consider the games to be canon. After the release of Wild Hunt, he became more hostile toward CD Projekt over their perceived mistreatment of the franchise, primarily over the Adaptation Displacement the games have caused to the original novels, regardless of reignited popularity of the books and their multilanguage translations. Sapkowski eventually hired a lawyer and attempted to sue CD Projekt in 2018 for having not received any money from their profits of the game series (despite selling them for a pocket change on his own without securing any further rights to any profits), as he had made a deal with CD Projekt when they created the first Witcher game. The case was dropped soon after, and the two would later sign a partnership deal, ending the feud.
Newbie Boom: Both the first and third games created a massive spike of popularity for the franchise, especially outside Poland and Czech Republic, while also reigniting and expanding fandom in those two countries. Wild Hunt in particular turned CDPR overnight into a major game studio, being a major success on all platforms and has been cited as one of the most influential open world role playing games of its decade.
The Other Darrin: Except for Geralt, Vesemir and Eskel, every recurring character has been recast at least once during the trilogy.
Sleeper Hit: The first game was a PC-only single player CRPG released in 2007 by a newly formed development studio, backed by a publisher largely unknown outside eastern Europe, along with being published internationally by a company that was slowly losing relevancy year by year, based off a fantasy setting almost unheard of in the English-speaking world. It proceeded to sell over a million copies in its first year of release. The success was such a surprise that the studio more or less apologized for their shoestring-budget hack job of a localization by using some of their windfall to produce a much more polished Updated Re-release with an expanded script and fully rerecorded voice acting.
There was a Witcher game in development from 1996-97 by Metropolis Software House, although it went nowhere and was unofficially cancelled. Interestingly, many of its supposed features (Geralt as the protagonist, dark and mature story, choice-based narrative) would be carried over into CD Projekt RED's Witcher games over a decade later.
The preview material for this project was the first time "Witcher" was used as an English translation of Wiedźmin, before the film went with "Hexer".
CD Projekt Red didn't initially plan to bring Geralt back to life in the first game. They originally intended to either have the player make their own Witcher character, or to have Berengar be the Player Character.
A remake of the first game for the Xbox 360 and Playstation 3 titled The Witcher: Rise of the White Wolf was announced in 2008. It was intended to have the same story as the PC Enhanced Edition, but feature a new engine and combat system more in line with the then-upcoming sequel The Witcher 2: Assassins of Kings. However, it was cancelled in 2009 due to disagreements between CD Projekt Red and co-developer Widescreen Games. However, in 2012, a group of modders endorsed by CD Projekt Red began work on an ambitious mod for the PC Enhanced Edition that introduced new story elements, a seriously overhauled interface, and updated graphics. The mod was released in 2014 to great acclaim and is now seen by many as the best way to play the original. A second attempt to remake the game has since been announced, though only time will tell if it comes out.