Cavill has an interest in video games as revealed in interviews. The actor had previously revealed how he almost missed out on the chance to play as Superman when he was too busy to answer Zack Snyder’s call about the casting for the Superman movie. Cavill also revealed that he recently replayed the entire The Witcher 3, and has also read the books in which the video games are based on.
Speaking on the books, the upcoming series will not be about the game but rather the original novels that were written by Andrzej Sapkowski. Sapkowski had previously expressed his opinion on how he felt that the games actually had a negative impact on his books, where many assumed the books were written after the game, and not before, and thus were viewed in a bad light.
That being said the actual TV series could also end up being different from what gamers remember about The Witcher, but whether or not this is a good or bad thing remains to be seen.