A yellowed, historical painting had hung on the wall of William's home for as long as he could remember. According to his mother, it was handed down from generation to generation in their family and had existed for more than three thousand years. William stared at the painting for a long time. It depicted an old chessboard with endless endgames, the folds on the board clearly visible. Numbers are engraved in the four corners of the board.  Although time has blurred them, the numbers are always in the same sequence--- 3, 1, 4, 2.

“Where's Daddy? I want to meet him!” William asked his mother frequently as a child.

"Your father has gone on an expedition and will come back with a lot of treasure in the future!" Mom answered him every time.

"I'm going to be an explorer and find a lot of treasures, too!" William's eyes shone brightly, as clear and shining as diamonds.

Ten years later, William’s original innocence had faded, and he had become a handsome teenager. He also became busier and busier, with many tasks waiting to be done, and he came home from boarding school less and less often. But after traveling thousands of miles to finally return home, he sat on the sofa in the living room, staring at the dusty painting on the wall. He reminisced about his childhood, remembering how he had said that he was going to be an explorer and go hunting for treasure like his father, and he laughed bitterly. He had not seen his father in all these years and was even hearing the details of his father from his mother less and less.

He slowly stood up and walked towards the painting. What did the painting really mean? Why has it existed in our home for more than four hundred years? His mind suddenly generated infinite curiosity and reverie.

He touched the painting lightly, and suddenly, the painting moved. He yelled; this was surely a mechanism! For so many years, he had never touched the painting like this, and so had never discovered this secret.

In front of him were an open door and a letter that had fallen to the ground. He picked up the letter, which seemed to depict a map, a map of this one chamber, unsigned, only a large W. Could this have something to do with my father? he thought excitedly. With this map, could I find him?

He gripped the map and walked forward. Boom! The door slammed shut behind him. He looked back to see that the intersection where he had entered had been blocked, and he could only keep moving forward according to the map. It was pitch black all around, and suddenly a red dot appeared in front of him, and he quickened his pace and ran towards it. The red dot came into focus as a button he pressed. He pressed it, and a door in front of him slowly opened again.

"Who are you and where are you from?" A voice came from William's side, but there was no one around him.

"I've come to find my father, William Potter!" he replied in as steady a voice as possible.

"Ha ha ha, another one to die!" The surrounding sounds grew wild, with a hint of evil in them.

"Do you know my father? He's dead?” William's voice trembled.

"Yes, he, like you, broke in at a very young age, and you know what it means to come in? You can't go out again unless you pass our test, but I’m sorry to tell you that from ancient times to the present, no one can get out of here, and you are only the next victim..."

Fear and regret swept through William's body, but he had no way back, and he walked forward hopelessly.

A huge battlefield, as well as a combination lock, was placed in front of him. The voice sounded again: "The rules are simple: complete this battle, help the White Army to win, and through this war crack the code, and you can go out." The voice faded and there was silence all around.

William stared at the battlefield, thinking that each soldier stood in a unique position, but it was clear that the White Army was at a disadvantage. He had never learned the art of war, and he was dazed in the face of the situation in front of him. However, he felt that this picture was strangely familiar. He pondered carefully, and suddenly, a thought flew through his mind- the positions of the Black Army and the White Army were very much like the positions of the black and white chess pieces on the chessboard painting hanging on the wall of his house.

Suddenly, there was a glimmer of hope in his eyes, as he realized it might be possible to solve the situation by recalling the pieces ’positions on the chessboard. But, he mused, “The winner of the endgame on the board is the black chess pieces, so ... the movements should be reversed!”

William suddenly became enlightened. A complete chessboard had been constructed in his mind, and he commanded the White Army, which moved in the opposite direction of the chessboard picture in his mind. "The White Army in the third row of the third column, take three steps back," he shouted.” "The first row of the fourth column should move one step to the left," he continued to scream. “The fourth row of the second column takes four steps forward, and the second row of the first column take two steps to the right.” Every time he finished commanding the White Army, the Black Army moved automatically in response, and his situation gradually improved, raising a proud smile on his face.

Then he heard a bang! The entire Black Army kneeled; he had succeeded. He let out a long breath.

"You're pretty clever, you broke this level..." The voices around him rang out again. The army that had been blocking his way disappeared in a blink of an eye, turning into a flat road that led to the combination lock...

William observed that the passcode lock had three chances of trial and error. After the third try, if unsuccessful, the system would crash. But there was no hint around. What does the password relate to? He was once again caught up in thought. Was there a connection with the battle just now? What is the connection? I just walked a total of four steps, didn't I? As if remembering something, he clicked on the passcode lock and entered the answer in his heart—the number of the black and white army separately.

There was a loud bang and a red warning appeared. "Input error! You have two more chances!

William took a cool breath. There were only two chances left and his heart fluttered wildly. What to do?

Okay, he tried to calm himself down, this code must have something to do with this war... maybe there’s a connection to war? Or the Chessboard? Could it be the position of the pieces on the board? Because the board is the opposite of each move, I had the White Army make, he reasoned, maybe I should have typed the password backward. He lit up with hope again, clicked on the combination lock, and entered it in reverse order, but what greeted him was an ominous warning.

He was in a cold sweat--there was only one last chance of trial-and-error left. Was his life really going to be lost here? No, no, no, no. His forehead was soon covered with sweat, and sweat ran down his cheeks, burning his heart. He gritted his teeth, his mind spinning, the code... password... His heart kept repeating the word.

He jerked his head up, remembering the disorganized numbers on the chessboard, four of which were still so clear after so many years -- the clues must have been hidden inside! His heart was pounding, mixed with tension and excitement. But what do these numbers mean?

There are four numbers that can be clearly seen, and the password of this mechanism happens to be four digits, so is the number of the password composed of the four digits of 1234? But why these four numbers? Does this number represent the number of times I moved to the White Army to the first level?

I moved the White Army four times in total, the first time I moved the White Army three steps backward. The second time I moved the other White Army one step to the left. By this reasoning, the third time I take another White Army four steps forward and the fourth time move another different White Army two steps to the right. It's that simple! Each time the position changes between these four numbers, so the meaning of these numbers represents the movement of the White Army position which is the same as the number order on the chessboard hanging on the wall! A smile instantly dotted William's cheek, 3142, as he confidently re-enters the password….

"Congratulations, the password was cracked! Go inside and see your reward! A clear bell sounded, the dusty door slowly opened, and William breathed a sigh of relief. What first appeared before his eyes was a ray of light. The air was mixed with the breath of history, and one painting after another was presented in front of him, all carrying the background and culture of their family. Rare treasures, golden splendor.

He walked slowly, carefully admiring these exquisite works, and unconsciously, his eyes were moist, and pride and excitement surged into his heart. He stopped and looked at the door, the unique architectural structure, unusual shape, and engravings of strange patterns, and suddenly the door was opened, and the voice sounded again, "Where the heart is, where the heart is, where it goes, born like a reverse brigade, a reed to sail, 3142, eternal.”

Then, a tall shadow came from the distance, and a proud tone came from it, "Congratulations, my son, your challenge was successful..."