O.k. I got the mechanics and it is actually quite a lot of fun. I really like the fact that we get a new minigame.
I do, however, have two complaints. First of all, why must we find chests with random rewards? I like the facts that this event is different from the other events, so I don't want to find the exact same chest from every other event. Why can't we just see what is hidden where as soon as the fog becomes light.
My second coplaint is that with this system lanterns and flash flasks are almost useless. A lantern can clear at most 5 and a flash flask at most 7 tiles. However, we do not need to clear the fog everywhere, as there are empty tiles or blocks hidden in the fog. We only need to clear the tiles moving foreward and the tiles where treasure is hidden. So there will be very few occasions (if any) where a lantern is worth more than 3 candles or a flash flask as much as 5 candles. Therefore I think the prices for the lights are wrong.