First off, really loved the intro, even the how to play transition, and the overall artwork is amazing! The colours and compositions used during the intro were great. Then in game, the environment and parallax are a nice little icing on the cake
Few little critiques:
For the shop, would be nice to have had like a spend 5, 10, 50 etc points on upgrades, spam clicking takes too long to upgrade.
Gameplay wise, personally it starts off a bit slow in terms of progression. Like the player could kill some weaker mobs for the initial coins and upgrades, then ramp up in difficulty and it wouldnt feel 'slow' But that could just be me D: Hope that makes sense. BUUT! The mechanics implemented are great and satisfying, and the rewind is a cool touch! Seriously awesome stuff!