It's a board game?
It's the digital counterpart to the upcoming FFG (the same guys behind the A Game of Thrones, Star Wars X-wing, and upcoming XCOM boardgames) that will release around the same time as the new Witcher videogame. This is meant to allow you to play single player with AIs or online with other people remotely. If I'm not mistaken, it will be offered to people who pre-order Witcher 3 or buy the boardgame itself.
how the hell is tabletop sim even legal with all those famous titles available in the workshop? some aren't even allowed in open source projects like vassal