No Game No Life Practical War Game Novel is written by Yuu Kamiya.

Before the creation of Disboard, a world where everything is decided by games, there raged a terrible war among the stars. But the Immanity weren’t the only ones fighting to end it-one elf had her own dreams for the future: “Whoever’s left standing once all the stars are destroyed is the winner.” In other words: anything goes! Follow Think Nirvalen’s exploits during the Great War along with several out-of-this-world short stories originally included in the anime’s bonus features!