BoxPop is a free, soothing puzzle game based on the chess concept 'knight's tour'

It may not look it at first, but BoxPop is a very interesting puzzle game. It's also free.

BoxPop is based on "knight's tour", which is a sequence of moves in chess that sees the knight piece visit every square on the board only once.

As such, each level has you moving across an irregular grid in an L-shape, trying to land on each square.

If you don't perform the sequence of moves in the right way then you won't be able to visit all of the squares. The challenge is to plan ahead or experiment on the fly to succeed.

What really drew me in to BoxPop is how it weaves the history of "knight's tour" between each level. You learn of how it originated as a concept in 9th century India, and how it has since been used for artistic purposes.

As with all good puzzle games, it teaches you to master a system, but goes further and passes on some worldly knowledge, too.