There is no cheat code to unlock all of the secrets, but I have full confidence in any player to earn all of the stamps! It’s super hard, but with practice you can do it!
I think its too difficult for me and sometime i dont have time to finish the game, i think you remove the super hard mode or at least give me a cheat or someone should give me a save file for anyone like me who dont complete super hard or if modern is too complicated.