Pretty interesting once you get over the initial hump. The game kinda threw you into the middle of the fight without any explanations, so like a lot of other players I was quite confused and needed to replay it a few times to get what was going on.
With the said however, I think there's a bug that hinders a good portion of the strategy of the game, which is that for me the dragging function to rearrange the card in my board doesn't function. So basically I just choose whatever upgrade I get without doing any other interactions, which I felt was quite limiting. Other than that the game mechanics seem to work fine. There some ok visual effects, but the most important ones I think that are missing the the one for actual player interaction with the UI elements. The game window was also the wrong size for my screen, so I had to zoom out on the web page to see fully.
Overall I think the concept has some potential, just needs to add more polish to it.