TState = (Closed, Open, Flagged);

    Open: array of Boolean;

    States: array of TState;

function FieldIsOpen(Field: TField; Row, Col: Integer): Boolean;

function FieldGetState(Field: TField; Row, Col: Integer): TState;

  FieldIsOpen := Field.Open[Row * Field.Cols + Col];

  FieldGetState := Field.States[Row * Field.Cols + Col];

  Field.Open[Index] := True;

  Field.States[Index] := Open;

procedure FieldFlagAtCursor(var Field: TField);
var
  Index: Integer;
begin
  Index := Field.CursorRow * Field.Cols + Field.CursorCol;
  case Field.States[Index] of
    Closed: Field.States[Index] := Flagged;
    Flagged: Field.States[Index] := Closed;
  end;
end;

      Field.Open[Index] := True;

      Field.States[Index] := Open;

  SetLength(Field.Open, Rows * Cols);

  SetLength(Field.States, Rows * Cols);

  for Index := 0 to Rows * Cols do Field.Open[Index] := False;

  for Index := 0 to Rows * Cols do Field.States[Index] := Closed;

      if FieldIsOpen(Field, Row, Col) then
        case FieldGet(Field, Row, Col) of

      case FieldGetState(Field, Row, Col) of
        Open: case FieldGet(Field, Row, Col) of

        end
      else Write('.');

        end;
        Closed: Write('.');
        Flagged: Write('?');
      end;

      'f': FieldFlagAtCursor(MainField);