I have to precise a rule for the pawn:
as in 2D, it will be blocked everytime it encounters a piece in the rook
like movement, even if there remains 4 more accessible positions (pawn
rule). This will prevent the pawn from promoting too easily and will keep
the knight useful !
The castling seems for the moment of no use, as the sides are opened, and
I don't go for adding more pawns, which would desequilibrate the game.