This is a fun game and I like the concept!
Overall it suffers from lack of clarity. Why am I losing lives if the pieces aren't ever actually attacking me? I understand that I'm in danger, but an animation to show them attacking or a more clear explanation of how losing health works would be great. There's also just a lot of stuff on the screen at once in the shop. Balatro separates the Blind selection from the shop for a reason, it gives the player a clear understanding of what choice they're meant to be making at that time. There are 2 types of things to purchase in the shop, but everything is very close to each other in the center because the deck UI is still on screen. Also, selecting a blind doesn't serve any purpose without the ability to skip a blind, it may be worth it to remove blind selection altogether and replace it with a Next button. Each food item should also have a specific food tied to the description, it was very confusing seeing 2 different foods in the shop that do the same thing. Only being able to play 2 cards is told to the player but is never shown during gameplay, and their is no live score total, just your current score and the multiplier, but I can't actually see what that score is at a glance. Some transparency on how much a move is about to score would be nice too.
If you take anything away from this: there is too much information on the shop screen, and it makes it difficult to understand the important information. Personally, I would give the Blind selection a separate screen after the shop or remove it entirely, and I would remove the hand section on the right, but maintain the run information and current foods/artifacts. Also, a new run should probably start either straight into the first blind or give the blind selection screen without the shop, as we don't have enough money to buy anything.
That was a lot of feedback and it was mostly negative, I know. I want to end off by saying that I did enjoy playing this! There is a lot of really good juice here, I especially like the way the chess board forms at the start of a match, how the cards come in to your hand, and all of the sound effects for performing actions. The style of the game is great, and this being a jam entry is SUPER impressive. It is very common for jam entries to suffer from these types of conveyance issues, and I think the underlying game here is fun and quite interesting. I hope this feedback is useful as you develop the game further, and that this didn't come across as too harsh!