A very nice and extremely challenging game, it took me hours to get through it but in the end I managed to unlock all the medals.
There seems to be a bug though, on my first run it only unlocked the 3 magician medals, so I actually had to do a whole second run (without cards), in which I unlocked the rest but STILL NOT the medal for collecting all cards. And since the cards are grey and uncollectible (because the game knows I already got them), and there's no "erase data" feature, I'm unable to collect them again, so I'm technically denied to unlock it...
That bug takes half a star away, but besides that the game deserves the remaining 4.5 stars. It's one of the hardest puzzle games I found here so far and the difficulty curve is mostly steadily rising, there are no hardcore levels in the beginning and no easy ones at the end. A usual flaw for many puzzle games.