Bloons TD but make it an Idle Upgrader. None of the panic or frustration but all of the satisfaction of bursting open the party decorations!
Slicing Cake is just perfect. The way the knife spins and carves through every pinata in its way gives me serotonin that none of the other Towers can compare to except fully upgraded Water Guns. I like to use Chocolate Fountains as speed traps to make the tankier pinatas stay in range of the knife and super soakers longer.
My only complaint is that I want to unlock even more Towers and Pinatas but that's just me being greedy.