Lately, Dakota and I have been spending some of our leisure time with Minecraft Pocket Edition and it's just great fun. It is surprisingly easy to lose oneself with the ostensible juvenile business of playing with blocks.
The reduced functionality and scope of the version on our iPads fits our play style quite well. Either device can act as an ad hoc server so we can share and build worlds together with no fuss or performance impact. The world is small enough to keep the session time from dragging on for too long but not so small as to become tedious.
Minecraft's huge wave of popularity has already surged and receded but, as any well conceived diversion, it continues to be rediscovered and enjoyed and deservedly so.