How can I kill the king?

Hint 1 of 6:

You need to make sure that all of the other enemy pieces on the screen are
gone first.

Hint 2 of 6:

The killer needs to move onto the square with the axe to kill the king.

Hint 3 of 6:

But if you go there immediately, the king still has a route of escape.  Try
blocking him off.

Hint 4 of 6:

Use the knight and the bowman to do so.

Hint 5 of 6:

The knight needs to stand directly on one of the squares to the king's side.

Hint 6 of 6:

And the bowman should guard the other square by aiming at it.  Put him on the
far end of the board opposite the king, so he's in line with the brown square
next to the king.