What is with this playfab?

[Caedo]

Hey everyone, was just curious why the game requires you to link your steam account to playfab and also what is playfab used for? i googled it but i cant seem to get a straight answer so if anyone knows the details and reasons, please let me know.

Cheers.

[Captain Conundrum]

Playfab (Formerly Ubernet) is the server-side infrastructure that is used for the multiplayer lobby. You will also need to log in to play on their servers if your PC doesn't meet the minimum requirements for offline play.

Up until this week's patch, all games were run through the Playfab servers even if they were single player. That changed with the offline patch, but you will still need it to play against other people.