Junos Arrow

From pluredro.com:

This is a restricted sliding block puzzle and its difficulty is extreme. Juno believes that most human beings cannot solve the puzzle without the aid of a computer. As he vaguely remember, Juno himself needed around two weeks to find one of the solutions, and the solution that he found requires more steps than the minimum movements needed to reach the goal.

Each sliding piece has grooves on two sides and one of the grooves goes halfway along the edge. A pin is set on the opposite side of the half-length groove. The tray also has grooves on two sides on the inside. These features give diabolically balanced restriction to the movement of the sliding pieces and makes the puzzle extremely difficult.

The object of the puzzle is to change the color and direction of the arrow. It requires more than 100 moves to reach the goal and there are lots of dead ends. There are nine challenges in total which can be played by changing the start and goal positions of the spacer (blank) piece. Most of these challenges require shorter moves compared to the initial problem on the first and the second image but it doesn't mean the challenge is easier. You will have no idea whether you are getting closer to the goal or not.