Hard Enough to Be Played Forever
The Threes story began on December 3, 2012, when Asher Vollmer, then a developer for the renowned indie studio Thatgamecompany, sent a prototype of a sliding numbers game to some friends. It was an ugly, bare-bones affair: a bunch of big, chunky numbers crammed inside a four by four grid. Within the hour, Greg Wohlwend, a graphic designer who had worked with Vollmer on an earlier mobile game, Puzzlejuice, sent a mock-up with nicer graphics. By the next day he’d sent a few more.
Read more at http://www.wired.com/2014/05/threes-game-design/