var
  VGameA: TGameA;
  VGameB: TGameB;
  a: TypeA;
  b: TypeB;
begin
  if Assigmed(game) then begin
    if (game is TGameB) then begin
      VGameB := game as TGameB;
      b := VGameB.B;
    end else if (game is TGameA) then begin
      VGameA := game as TGameA;
      a := VGameA.A;
    end;
  end;