Head over to https://www.gog.com/ to grab you free copy of this game. Follow these easy steps to claim it.
- Make an account on GOG
- Sign up for the news letter
- Then add Gwent to your library
- You can then purchase The Witcher: Enhanced Edition for free
CD Projekt Red is doing this as a promotion for their card game Gwent. I have never played Gwent, or a Witcher game, but this does give good incentive to try them out.