I randomly stumbled upon your dev log on yt and had to give it a try.
It's a cool concept, and the game just needs a little more polish.
I haven't seen anyone mention this yet, but I noticed the movement doesn't seem to be normalized, so the player moves faster when going diagonally. That's an easy fix by applying .normalize() to the input vector.
Also, art-wise, since you chose a pixel art style, I'd try to stay consistent with it throughout the game and avoid using "mixels" (pixel art with different pixel sizes). I noticed the text isn't using a pixel font and cards in the gun have a smaller pixel size, which makes them feel a bit out of place.
And like others have already said, after a while the enemies run out or spawn too slowly. A system that ensures there are always around 15 silly enemies on the map could help, or simply increasing the spawn rate - maybe even making it ramp up over time to see how long the player can survive.