Huge Chess: new form of chess

The game can only be played on a computer screen, as the size is 24 * 24 squares, with 3 sets of pieces per player, at the start the player can arrange the pieces behind the pawns anyway they wish, but there is a time limit to this otherwise the pieces are arranged as normal by the computer program.  Basically it is huge chess with 3 kings, 3 queens, 6 rooks, 6 bishops and 6 knights with 24 pawns.  

A win is obtained when all 3 kings have been mated, once the king is mated it is taken off the board.

In case more than one king is checked at a time, only one king can be moved at a time, the other king or kings are considered mated. So if you check 3 kings at once with a piece, 2 kings are considered mated and taken off the board.

Time requirements for each game are tripled, so blitz is 9 minutes, rapid 45 minutes  and classical 6 hours.

I'll leave it for someone else to program the interface for this game.

Due to the size of the game, the program will be required to check that the move is legal before it can be played.