type Ground_Abstract is abstract tagged null record;
function Status (Ground : in Ground_Abstract'Class) return Game_Status_Type is abstract;

type Chess_Ground is new Ground_Abstract with
      record
         Current_Player      : Player_Type := light;
         ...
      end record;
function Status (Ground : in Chess_Ground'class) return Game_Status_Type;

function Self_Game(Name : in Games_Type) return Samples_Access is
      Result : Samples_Access;
      Game   : Game_Type;
   begin
 
      case Name is
         when Chess =>
            declare
               Samples : Sample_Vector.Vector;
               System : System_Type;
            begin
               Game.Game := new Games.Chess.Chess_Game;
               if Game.Game = null then
                  raise Program_Error;
               end if;
               Game.Game.Ground := new Games.Chess.Chess_Ground'class ' (Games.Chess.Initialize);
 
               while Game.Game.Ground.Status = Continue loop
                  Games.Chess.To_Play(Game.Game.Ground.all, System);
                  Samples := Samples & Encode(System);
               end loop;