"Fancy yourself as being pretty bright? Reckon you're good with spatial puzzles? Prepare to be demoralised. IQ Challenge:Slider is a Symbian implementation of the classic slider puzzles that the elder among us played as a kid in the 1960s. With complete control over the size of the puzzle and how badly shuffled it is, there's a challenge in here for everyone" - Steve from AAS (http://www.allaboutsymbian.com/flow/item/16857_IQ_ChallengeSlider_isnt_k...)
Now it has been ported to Android: the classic number puzzle with many customization options, UNLIMITED levels up on your own settings.
Complexity can be set from easy to extremely challenging independently from size of the puzzle (from 3x3 to 10x10)