good stuff, very well made for 72h, here's a few suggestions if you want to put some more work in
the heart system doesn't work very well with this game, the combat is messy and taking hits doesn't feel like it's my fault.
i recommend either embrace the messy combat and make it more lenient in taking hits or making it more methodical and improve the aiming and remove hit on contact (make the enemies need to perform a action to damage the player rather than just touching)
the effects feel messy too, hard to know what's going on, would be good to make enemies and enemy projectiles stand out from the player attack effects.
the hammerhead and the mage wand don't feel like enough of a upgrade from the claymore(or even sidegrade), and the robot just sucks in general, would be worth it for 100 souls maybe? extra heart beats it easily, would be good to be able to improve movement speed other than the dash and also a combo system to increase the depth of the gameplay