Skullduggery! is an action physics based platformer that is free to play and include a singular in app purchase of $4.99 to unlock the full title.
Pro Challenging gameplay
The gameplay in Skullduggery! is challenging without being to tough, there is always a bullet time mechanic players can use that can make some of the tougher areas a little more easy. So really it can be up to the player how difficult they want the gameplay to be.