Ok, we all know why we are here and why we play this game, and as much as it might be a shock to the dev(s?) it's not for the riveting, action packed gameplay.
So here are some suggestions I have for the actual main part of the game:
1. Add a "favourite" button to cards and a "favourite" category to a dropdown menu in the gallery, for example in the "regions" one, just like we have "active regions" in there.
2. Allow scroling while the picture is in an enlarged / full screen mode.
3. Mobile version - Adjust the scrolling so you don't have to move the picture so far for it to switch to another, right now it feels sluggish and it's hard to do with left hand while drinking tea with the other one. Or just add arrows on the sides that player can click instead of sliding the picture.
4. Mobile version - Either turn off completly or have a toggle option in game to stop the rotation, the game doesn't self adjust to rotated screen and generaly would be unplayable in landscape mode.
Otherwise, solid "game".