Mystery of the Skulls is downloadable DLC for the Game. This adds 17 new mini levels. Inside many levels of the original game you will now have skulls marked on them. This will add a portal to the level. Once entering you will enter a dark version of the area with red wavy lines that remove all stonified me's on the stage. The goal of these levels is to collect the skull in the level and then return through the exit portal. There are 17 skulls to find.