There is a possibility that the game actually has a hidden “production mode” where it allows offline play. Make sense though because the game developers must be able to run the game during production where the server hasn’t been up yet. Research into the possibility of reenabling this mode in retail build seems to be losing steam though. Looks like it picked up some steam again: https://steamcommunity.com/app/241560/discussions/0/4306075118785997064/