13051  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 adjusts 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 microorganism 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 SuperVillain 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 . 