Enjoyable game with a good foundation to improve on. I do like the twist on the minesweeper formula as well as the graphical style, but once you go through the three maps, there's not much left to it.
More set maps would be nice for a sequel, as well as the untimed casual mode using randomly generated maps or maps generated based on parameters set by the user (map size, number of treasures, etc) would be a huge boost to the longevity of the game. On an untimed mode though, considering the challenge is based on penalizing you for digging in the wrong spots and taking damage from traps, it would be easy for people to game the system and just dig all around a clue until they find it. You may want to consider a way to avoid that, like dig three incorrect spots in a row and you lose.