Great game, of course. My most urgent message is that the volume sliders, at zero, do not bring the volume to zero. Oops.
Also, it is most painful when a skull pushes an enemy into you. Perhaps this is a necessary challenge to make skulls a less obvious choice, but perhaps making them ghost skulls instead or something could ease this problem. Or maybe that could be an upgrade card for the skulls?
I think I lost half of my 8 hearts to skulls unpredictably pushing cars into my trajectory on the Day 1 challenge with 440 enemies left lolol. The pain was real.
Also if the game thinks every enemy is spawned in, you can just kill them all instantly if you get the cursed enemy wipe upgrade for a heart. I'm pretty sure there were still hundreds of enemies killed but I basically won for free on the Day 2 challenge probably about 2/3 through.