Chess puzzles - attack learning for kids

I created this game for my children to learn how to play Chess and learn the basics of attack and capture pieces on the board.
Game details (play this game offline):
• The goal of the game is to have only one piece left on the board;
• The board may have more than one solution.
• To play the game, move the pieces on the board to capture other pieces;
• To move a piece on the board, tap or drag the piece; A blue square shows and it means it is selected or it shows where the piece came from when you dragged it; You can also tap on the piece that you want to capture.
You can rate individual board from 1 to 5 stars to know how difficult was the game when you are looking in the games' history.
You can receive challenging games.
Restrictions:
• With every move you need to capture a piece;
• Moving to an empty cell is not allowed;
• If the King is on the board, it needs to be the last piece on the board.
Premium features:
Location to move a piece, it displays the green square for the places that a piece can move to. When the user selects a piece that wants to be moved, this feature will highlight the places where it can go with a green square. This feature is helpful for children to learn how to move pieces. The first move on each game has this option free.
• Undo moves, it goes back one or more moves. You have a free undo per game. You can use this feature to don't show the number of tries.
• Suggestion, it shows what the next move is and if you can finish the game with the pieces left on the table. You have a free undo per game.
• Remove ads, it removes the ads from the game.
• You can also buy all the premium features from the game or you can subscribe.