I've got the same problem (we should maybe merge the threads )
Played 60 hours before the patch, but now I can't
- start a new single player game
- continue an old single player game
- join my running game with my friends
It always crashes to desktop without any messages whatsoever. I also couldn't find any log I could look at for messages to attach. I am also not aware of any debug/log switches I could flip.
My setup (quite an old rig, but could run Grounded without problems before):
Let me know if I can do something to provide further help in analyzing this problem.