No Game No Life, Vol. 1 (light novel)

In a world where games decide everything - even national borders - a genius brother-sister duo aim to put their gamesmanship to the test...to save humanity!
In this fantasy world, everything's a game--and these gamer siblings play to win! Meet Sora and Shiro, a brother and sister who are loser shut-ins by normal standards. But these siblings don't play by the rules of the 'crappy game' that is average society