I played this some days ago and I really like the card game you've put together here. The way the story revolves around the cards is also nicely done, despite the minor inconsistencies here and there. I'm not quite sure if it was intended to be this way, but I feel like I missed out on a lot of events in the first town when the story forced me to progress. It would be nice to be able to have more time to explore that, because until the demons attacked, I didn't get to see Isolde once and then was best friends with her all of a sudden.
I've noticed that the portrait stays visible and obscures half the menu when you try to save during a conversation.
There seems to be a bug that appeared a couple of times during a card game, where a card would wrongly be converted. This only happened when the last card played converts another card. For example I have cards at top middle, with a 5 on the left side, and one middle left, with a 2 on the top. Now when the enemy would play a card with all fours in the top left corner, both of my cards could be converted. This is inconsistent though and does not always happen. Probably just with certain cards/values playing into eachother.
While I have to say that the AI art is quite nice, I'd like to point out that some backgrounds should be reworked or exchanged. There are just way too many doors, often times even several in the same door frame. IIRC the brothel background was one of those.
It would be nice to have the background go along with the conversations, as I found myself looking at the empty inn while talking to anya or the other girls working there. Especially so since there seem to be backgrounds with those girls in the scene already being used to some extend. Why not use them more?
I played my first couple of matches with silver cards only because I didn't realize that I was given a gold card too. Maybe you could add a counter on the respective tabs in the card menu, so that the player sees that there are cards in other tabs as well.
Lastly, I'd like to suggest something about how the card game works. After fighting ravenna a couple of times, I managed to get a draw. I know this battle is supposed to be unwinnable, but at that point there was some hope that a win was actually possible if the events beforehand were handled better than what I did. So, being able to get this strong to be able to pull a draw on one of the supposedly strongest enemies there would be, seems to be a bad set up for later on. The S on some of ravenna's seems to be trump, which is totally okay for her to have. She is supposed to be a very strong opponent, but it also tells me that there are only 9 values on the cards. And me having several cards with 7 and 8 values on them after what seems to be part one of the story, leaves me with almost no way to improve before capping out completely. There are several ways to counter this though, for example you could expand the values to include double digits; or you could rebalance the current cards to have lower values alltogether to have more room to grow. Another way would be to add a twist to the game where you include 0 and have it beat S but lose against numbers.
But these are just suggestions and I don't intend to dictate how you make your game. It is yours and I already like it the way it is. I just wanted to throw in some ideas with my feedback