I beat this game on expert and still don't know how it works, which is probably the first time ever that I can say that about any game.
you make four piles of four symbols. each card is a symbol and also shows you which other symbols may be placed on it.
what's missing for you
Expert: Each row and column of 4 cards are only allowed to have 1 of each symbol. In casual you can have 4 diamonds in a row (first cards in each column), that's not allowed in expert.
