The absolutely right way to go about it is not to hide this art style in a memory game, but to use these excellent game mechanics to create a very good card game!
Terrific.
More animations when playing a card communicate better to the player what is happening. For example, the discount on a card could fly off to the side as a symbol and land on the next card (discount). This way, the player knows where everything comes from and understands it more quickly (not that it's not easy to understand as it is!).
Perhaps this would also help explain the “energy” concept behind the cards to be played to the player. This is essential for understanding the game and allows for real tactical maneuvers with shields (and all the other ideas you surely have).
I would also like to see how many cards my opponent has left in their hand so that I can gamble on how much energy I give them for their next move. Especially with the shields and stuff... well, you know better than I do :)
I can well imagine that unlocking characters in stages could be a good long-term motivation if they can be sorted by difficulty.
I really enjoyed the sound, the design, the whole thing.
Definitely keep developing it... it's really, really good!