No Game No Life (Light Novel) Vol. 08

Just as the end of Sora and Shiro's dice game against the Old Deus approaches, they are faced with completing Jibril's task--a strategic simulation game set in a reproduction of the ancient Great War, before everything changed.
As the leaders of the weakest race, the Immanity, the gamer siblings have one objective: ensure that in this version of the Great War, no one dies.