Playing for the first time. PC is usually off internet (I'm very rural and have to use my phone as a hot spot). Return to the map after beating the first quest and receive a 'could not process map client message' error, which prevents me from loading the map or continuing the game. This error persists even after reboot.

When I finally try playing with internet...lo, it works, and I see that an achievement pops up.

It seems like the game will not let you continue playing unless you are online.