A Maximummer is a chess problem in which Black is required to consistently make the longest legal move, with preference given to one of the longest moves when there are multiple options. Another variant, known as Double-maximummers, extends this rule to both players, obliging both sides to play the (geometrically) longest legal moves possible. The concept of Maximummer was introduced by T. R. Dawson in 1913 and is commonly applied in selfmate problems within the realm of fairy chess conditions.
When a player is under check, they are required to defend against the check using the longest possible move that effectively addresses the threat. The measurement of distances is based on the center of the starting square to the center of the destination square.
Let’s take a look at the following problem: