Version 0.1.6 is live, and we believe it fixes your freeze. In a pit dug as fully as yours, every brattice cloth sits on a face at a junction, and an overcast built next to one pointed the air model at a junction it did not have. One error then stopped the game drawing. When you continue your saved pit, those cloths come down with their £15 refunded. We rebuilt a pit like yours and pressed regulators, overcasts and doors beside the upcast 4,000 times with no freeze. If anything still goes wrong, please tell us here.