"No Game No Life - Practical War Game" by Kamiya Yuu. The "practical" bit in the title is in contrast with the "abstract" games that appear in other volumes. In this volume, characters fight to their death.
Four side stories are collected in this volume: how the elves attempted world domination before the current game rules are put in place, an interlude of how Steph almost managed to win against Sora, backstory of the friendship between Fil and Kurami and why they wanted to take over Elkia, and epic diary of how Jibril defeated a dragon. Most of these are prequels, but they are not required reading for the continuity in the main story line, unlike volume 6.
The subtle lack of chess pieces on the cover and the not so subtle absence of volume number might suggest that this is a volume to be skipped, but skipping it would be a real shame. Not so much for missing out on the elves or Steph's transformation into a pervert (which came with a totally unnecessary but absolutely glorious illustration, in full color). The pages that made it all worthwhile was Jibril's repeated attempt to kill a white dragon.
Back in the times when flügels were still killing things and collecting heads as a sport, Jibril had her sight set on killing this dragon. Thanks to the "practical" nature of this volume, her various attempts are depicted in vivid fight scenes rarely seen elsewhere in this series. The flügels were clearly a weaker race compared to dragons and Jibril solo attempt to fight a dragon seems foolish, yet she persisted. This is very much the No Game No Life spirit, and the game here is the head of a giant lizard. Jibril would eventually win, the same way that the weak humans would win against flügels thanks to Sora and Shiro.
This was a much more pleasant prequel than volume 6, and I am glad we got to see how the usual characters managed in a more hostile setting.
Previous (2017-03-12): "Imouto sae Ireba Ii" volume 6 by Hirasaka Yomi
Next (2017-04-26): "Kumo Otoko" by Edogawa Ranpo