This is really cool- and honestly a pretty unique idea I haven't really seen before in one of these jams. Smashing the ghosts feels satisfying, and the music contributes a lot towards getting you in that flow state of smashing ghosts as they pop up.
That being said- it doesn't feel like there's too much of a progression. I played until like defiance 6 or so (I think that number is how many times you've revived)- but stopped there because I always had more than enough money to buy the revive +10 max hp. I can tell that the game gets objectively harder- the ghosts get faster and attack more often, but I didn't really feel like it made that much of a difference since my health was always increasing enough to offset it.
Maybe it's just a case of having the price of that particular upgrade scale harder? Idk, I know it's always hard to balance these games in such a short time- but it always feels bad to quit an arcade game out of attrition over losing.
Regardless though, great job! I definitely enjoyed playing