Really enjoying the game so far! I think you've hit on something special with the core mechanics and I hope you keep refining it with future updates!
-Absolutely love that the decks are persistent between runs and that you can build your ideal deck over the course of many runs. It feels like you're crafting your own custom class and helps mitigate the burnout I typically feel in rougelike/lite games.
-Controls are super responsive
-Art direction and color palette are beautiful
-Played at 1080 and had no performance issues or frame drops that I could see. Encountered no glitches either.
-Enemies blend into the environment a lot and can just appear right ontop of you. Altering the sprites just a little to make them stand out more and/or adding sound/graphical effects to indicate when they're spawing would be a huge help.
-When you first enter a level the enemies spawn and start attacking immediately. There ought to be a slight delay, or at least you should be immune until after the initial card-draw animation.
-When you're removing a card from your deck mid-run it would be nice if idendical cards are displayed next to one another, so you can more easily see how many you have of each.
-I've only made it a little past 1000m so far, but it seems like it just goes infinitely? Might be wrong. But it might feel more rewarding if there was a clear end point. Or if you want to keep it as an infinite runner, defined break points where you get a larger reward and can take a bit of a breather between levels.
Anyways I hope that feedback is helpful! Can't wait to see what you do with this game going forward,