He's made into a blank slate for players unfamiliar with the universe. This isn't to say they're not good games, but in order to start anew with its own canon separate from the books, CD Projekt Red gave Geralt amnesia at the beginning of the first game.
The Witcher 1 and 2 aren't necessary in the slightest. If you're dying for more Witcher but don't want to commit to reading eight novels, here's how to get into the games, including what to play, what kind of PC you'll need to run them, and how to customize the experience to suit your playstyle. For those whose first introduction to The Witcher is through the Netflix series, getting into the games might be daunting.
