The following segment is lifted from http://www.joshuakennon.com/i-beat-cookie-clicker/ which wraps up the mental hooks cookie clicker hooks into.
This entire game is based largely upon a single mental model: The illusion of growth.  It hijacks the neural system to provide a dopamine reward based on seeing the numbers escalate, and the reason it’s so appealing is Orteil has put a lot of thought into the mathematical relationships necessary to keep the next achievement just out of reach, while still feeling fair.  This is worthy of a case study. 

Recently I've moved on to a retina MacBook Pro which has an external 23 inch external monitor attached to it. So with iPad storyboards, it would be great to have Xcode on both my screens. I looked around and the following method seems to me is the best and easiest solution. Ive' tested it on Xcode 5+ and seems to work great. Have a look.

http://blog.brunophilipe.com/2013/03/use-xcode-on-multiple-screens-the-easy-way/

Naughty dog is one of those companies that keeps on delivering great experiences after the next. This is in part because of the great personalities that consist within the company and in part because of the creative freedom that Sony has given them. Here is an in depth commentary of the history of one of my favourite game developers out there at the moment.