@Milanin its the author taking artistic license with the concept inorder to keep things interesting. also, the series doesnt flat out state the game interface is based on minecraft, just a minecraft analog. Im curious how he is going to explain the enchanting table, i highly doubt hes going to spen XP to enchant stuff.
@Kizuro
It's perspective, even a perfectly straight line will look curved over a distance, there's also the theory that nothing is straight and everything is a curve