Very eager to play it. One question: the Tests are resolved when at least one PC has succeded the roll, or all the PCs must reroll until they succeed?
Great question! Everyone makes one roll per test. If you succeed, you proceed unharmed. If you fail, you still continue on but you gain a Mark. The only thing that stalls the progress of the survivors is if they all die.
I have seen people narrate this in cool ways. You could fail a roll and describe yourself facing the obstacle decisively and competently, but walk away Haunted by the memory of what you faced.
This procedure is clarified a bit in the updated version we're laying out now.