The Knight's Tour Game 3D

In this game, you are challenged to solve the famous Knight's Tour problem. The main objective is reach every position in a chessboard with the Knight and its usual "L" move. This is a famous mathematical problem proposed around the 9th Century A.D. You can try the traditional Chessboard 8 x 8. If you never knew this problem, you can try the 5 x 5. However, if you are a genius, I challenge you to complete the 20 x 20 chessboard. Are you smart enough to complete this task?