 Chen felt that the reason that Cloud had been so warmly received was because the emotions it sparked in players were different than any other game available at the time , and believed that it was his " calling " to make more games that changed what people saw video games as . Chen went on to do his master 's thesis the following year in the concept of dynamic difficulty adjustment , where the game <unk> how it reacts to the player based on the past and present actions of that player . Chen illustrated his ideas with Flow , a Flash game made with Nicholas Clark . The game involves the player guiding an aquatic <unk> through various depths of the ocean , consuming other organisms and evolving in the process . It was released in March 2006 ; it received 100 @,@ 000 downloads in its first two weeks and by July had been downloaded over 650 @,@ 000 times . A PlayStation 3 version was announced in May 2006 as a downloadable game via the PlayStation Store , and was released in February 2007 . A version for the PlayStation Portable , developed by <unk> Studios , was released in March 2008 . Flow became the most downloaded game on the PlayStation Network in 2007 , and won Best Downloadable Game at the Game Developers Choice Awards . 
