I suggest as a market system, Merchants who arrive at the village periodically with random items for sale, That way you can sell your 999 Rusty screws, Buy some of the items you need or low on, but Still have to grind for specific items that are unavailable at the store.
Will there never be an offline mode for this game? I was in the middle of a single player campaign battle, My connection cut out and the whole game died.
The only thing I didn't like is how the game turned from a Sudoku like elimination puzzle, into a guessing puzzle after level 7, otherwise great game.
The shapes did NOT make sense though.