SwipeBlackSkullBack? app for iPhone and iPad

On a Halloween evening, Joe sat home alone. Without a single friend for company to trudge the twilight streets, he resigned himself to a memory matching game featuring colored skulls in honor of the macabre holiday. Sugar hyped urchins with horns and fangs screamed at Joe through the front door.
"Trick or treat! Trick or treat!"
"I dare you trick me, snot nosed imps", Joe screamed. "I dare you and all spirits of this sinister night to do your worst!" All of a sudden the screeching voices fell silent. Upon returning to his game Joe was a little frightened to find it changed for the worst...

Tapping white skulls reveals colors. The object is to tap and find matching pairs. Swipe black skulls up as they descend. If a black skull gets to the bottom the game is over. Sometimes a grey skull covers a white skull position. Dragging it off a white skull allows for revealing of the white skull. After dragging a grey skull, once released it returns to its starting position. Progression through levels increases the speed of black skulls and reduces their size, increases the number of white skulls and the number of grey skulls.