This very much feels like a Zen game, the music and soft colors is so relaxing, and the well executed matching game compliments that vibe perfectly. There's so much content in here too which is awesome! As other people have noted though, the game's pace could be a bit faster. I don't know what kind of bugs this would cause, but I think allowing the player to choose their next card directly after getting a successful pair, instead of waiting for the pair to go all the way to their hand would be a very welcome adjustment.
Awesome work!