Spooklands will be universal
Game is now releasing August 14th, will be $0.99, no IAP
New info and images
That yellow creature is our version of the Boitatá. Actually, it's the exploding version of it, which means that in the above picture killing one of them would probably set off a chain reaction that'd wipe out everything on the screen. The regular Boitatá you can see in screenshot below (they're the little brown creatures.)
What you're seeing above is the "Edible Snail" powerup, which causes everything to go slowmo for a little while, allowing you to place as many shots as you can until time reverts back to normal!