Nice one, the visuals and audio are really nice.
As mentioned in another comment I didn't really understand how the shop was meant to work. I could sell cards, but didn't seem to buy new ones? Maybe it's related to the bug you mentioned.
Thanks for trying out our game!
We'll have to figure out a better way to communicate this. Basically you have to sell a card to buy more cards. But if you sell more cards than you buy, the game will refill your deck with low-tier cards. This is to ensure that your deck is always at 20 cards.
If you used the black-bar card with the orange border, then yes the bug mentioned below applies and that could also be why it would not let you buy cards.
We are sorry that your experience was inhibited by these issue. We plan to fix, rework, and add content after the voting time is over
Thanks!