Grid Chess

In 1953, this game was introduced by Walter Stead. The game is popular is chess variant circles, but also with problemists.

Rules

The board is divided in 16 regions, each of two by two squares. All rules are the same as in orthodox chess, with one additional rule: when a piece moves, it must move to another region. I.e., the board with opening setup looks like this:

A king is only checked by a piece that can move to the square where the king is standing, e.g., a king on d1 is not checked by a queen on c1.