"No Game No Life" volume 2 by Kamiya Yuu. The opening chapter had some very interesting remarks about why game rules are absolute while real life rules are not, though the majority of the volume was not directly focused on this distinction. This could have been a very philosophical book, but what we got instead is the most exciting match of shiritori.
Actually, what we got was a very vivid demonstration of what would happen if the universe were governed by rules fitting for a game universe. If any rule was possible, and knowing that most readers just like to see stuff blow up, a very good plot would be to change the laws of physics and destroy the universe. And that is exactly what happened, I couldn't have asked for more.
For anime viewers, episodes 5 through 8 are an accurate adaption of volume 2, minus a few details. One particular detail that got left out was that Sora did not prepare one piece of paper for the final response, he prepared 20 variations. Things are actually not as reckless as they might seem.
Just before another lively chapter of the author's afterword, the main story ended on a cliffhanger (anime episode 8 ended on the same cliffhanger). Looking forward to volume 3.
Previous (2014-09-04): "What If?" by Randall Munroe
Next (2014-09-25): "No Game No Life" volume 3 by Kamiya Yuu