This, for me, has been one of my favorites of the jam! Simple, clean pixel art, easy to pick up mechanics, and a collection of interesting upgrades to play with that enhance an already engaging core loop.
The randomness afforded by the shop along with the ability to reroll your deck of upgrades added a good sense of risk vs. reward to the point management. I could choose to go several phases without buying anything and freely go on a shopping spree, but having to manage health between phases meant that many points went towards maintaining and pushing the deck to include as many heals as possible.
The one thing I'd like to see added is regarding enemy spawns. The effect for when an enemy spawns is almost instantaneous, and a good amount of damage taken was an enemy spawning on top of me at an inopportune time. A bit of extra time where some audio queue could play, and a longer visual to indicate where an enemy is spawning would go a long way into improving the overall experience of the game.
Superb work!