PlaSmart Perplexus Maze

It looks innocent enough — almost like a toddler toy, in fact — but Perplexus’ happy round surface belies the serious brain-teaser beneath. The object is simple: Get the sphere from one end of the 3-D maze to the other. But start down one path, and you’re likely to be thrown by any number of challenges — not the least of which is the gravity you have to manipulate to get the ball up, over and around certain areas. Luckily, there are several stops in the maze where you can resume play (to use a concept borrowed from video games) once you drop the ball — but that doesn’t make it any easier to pick things up from there.

$28.45 from Amazon.