LOL, it isn't based on video game at all. There is a series of actual fantasy books written by Andrzej Sapkowski that serves as a basis for the show. See https://en.wikipedia.org/wiki/The_Witcher
However, they made a rookie mistake and started filming Sapkowski's source material in the order it was written, i.e. starting with short stories, which is why the show does not make sense: each episode is a separate story, not connected to previous episodes. They should have started with the 5-book saga, and maybe throw some of the short stories as flashbacks.
Show also lacks the proper introduction of characters and the world's mythology. I am a fan of the books, so it all made sense to me, but wider audience might have a trouble making sense of all Wither abilities, Law of Suprise, etc.
Honestly it's really hard to do it, to appeal to both the gamers and the wider audience who never touched the game (inc the critics)
I'm playing games since the late 80s and seen so many movies and TV shows failing.
This list is perfect https://en.wikipedia.org/wiki/List_of_films_based_on_video_g...