If this query param is added, on board at two empty spaces two boxes will be present. User's avatar can't cross the box, it has to go around it.
If somebody finishes the game in high difficulty mode, 3 moves will be deducted from their moves count. This is done to give them some incentive to play high difficulty. Otherwise they won't be able to compete on ScoreBoard
A difficult mode of the game can be added.
?difficulty=high