* Piece
position: pair<x, y>
enum Direction(NONE, NORHT, SOUTH, EAST, WEST)
** Pawn
origin: Direction
** Wall
direction: Direction
* Board
pieces: array< 9, array<9, Cell>>
* Cell
ocupant: optional<Pawn>>
trench:  Trench
* Trench
NorthOcupied: bit;
SouthOcupied: bit;
EastOcupied: bit;
WestOcupied: bit;
* PiecesPool
pawns: array<4, Pawn>
walls: array<20, Wall>
* Player<int N>
walls: array<N, Wall>