You were supposed to move the black one. Now it worked, but it is movable outside where it should be movable.

Are you supposed to move the black king as well inbetween the moves of the white pieces or why is the black one moveable?

It's a classic mate in 2 chess puzzle that originally was mate in 3. I made the first move, since not everyone is a chess pro. After every attempt you need to reset the pieces to the original spot as shown on the wall picture. Remember there are many ways to get mate in 3 but you are looking for the only way to get mate in 2.

Hint 1: All the pieces are on a single axis slider. This in turn limits most pieces to only make about half the moves as possible.
Hint 2: The Bishop is first to move (D5), thus leaving you with only 4 moves possible to start.

Need some hints for chess