I recommend a novel where the male protagonist plays a game with King Arthur as the theme and later transmigrated into the plot of Fate/Zero.

The male protagonist played a game. In the game, it was King Arthur. Later, he crossed into the fatezero novel.

Answer 1

"Playing Games to Become Immortals" is a sci-fi novel written by the author, Wang Luoyi. The general plot of this novel is:

In this day and age, even a fall could transmigrate, so it was fine to wear it. It was just that, uh, he had transmigrated into the game. Alright, then I'll cultivate in the game! Wait a minute. It seemed. It was true…
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"Swordsman in the Game World" was a game novel written by the author, Buchong Zhengye. The general plot of the novel was:

When the gaming geek was still immersed in the Internet, a trip that he said would take him to another world. In fact, there was nothing wrong with transmigrating-if he hadn't transmigrated into a sword...
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"The Lord Hunted by Games" was a novel written by the author Meow, who loved to write books. The general plot of this novel was:

The protagonist, who had transmigrated to become the son of a great aristocrat, was suddenly bound by a dangerous game system while enjoying his life.
From then on, he would have to experience the hunting of soldiers and even armies in the games he had played before, such as riding horses and killing, and total war.
After every chase, he could obtain a considerable amount of game rewards. In order to resist the pursuit that was stronger and stronger, he could only become a revolutionary pioneer, a conqueror, and even an emperor, building a powerful army to fight against the game.
Conquer the entire world at the same time!
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"The Supreme Overlord of Online Games" was a novel written by Little King Carp. The general plot of the novel was:

The protagonist's parents were reborn! Tell the protagonist that there is a game that allows people to transmigrate to a fantasy world! Originally, the protagonist thought that by relying on his parents 'rebirth experience, he could be one step ahead and obtain the epic legendary mission, snatch the divine artifact, kill the divine beast, and flirt with the goddess. From then on, he would reach the peak of his life! However, when he entered the game, he realized that everything was fake! Not only was there nothing, he couldn't even log out of the game…
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For the Glory of Warriors was a novel written by the author, Capo. The general plot of the novel was:

The gaming otaku Eze brought the "Attribute Panel" to a real game world and became a declining Divine Warrior. With the "Game View", he began a legend of fighting for glory!
Blood and power!
Anger and Punishment!
Duty and glory!
Holy Light and Evil!
How could a warrior retreat?
Heaven to the left, warriors to the right!
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The book "The Witcher Lord" was a novel written by the author, Death Wing Neltharion. The general plot of the novel was:

This was the story of a technological geek saving the world.
The otaku Roddy, who was addicted to games and alienated from real life, was one of the most famous Rangers in "Earth Splitter." However, a transmigration had allowed him to accidentally enter the game world and return to the subtle historical node two years before the server opened.
The destroyed country was still maintained, and the woman he loved had not died in the war of the orcs.
The shadow of the undead was still lingering at the border, and the hypocritical masks of the nobles had yet to be removed.
Before all of this happened, Rody found that all he could do was hold his bow and arrow tightly. He looked at the land that had not fallen apart due to the disaster and embarked on a journey that was destined to become an epic.
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This Player Has a Big Problem was a light novel written by the author, I Have Love. It was a fantasy novel. The general plot of this novel was:

This was the story of a man who gradually realized his fate.
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"Yu-Gi-Oh's PL System" was a light novel by the author, Chairman Ou of the Universe Finance Group. The general plot of the novel was:

Bringing the System to travel through Yu-Gi-Oh! PM , striving to change the plot of the animation and not leave any regrets in childhood! P.S. Plot Progress: Kingdom of Mouth-City of Rules-Chrono Duel-Domadazi-KC Entertainment-King's Memory.
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"I'm Just Playing a Game" was a fantasy novel written by the author, Big Boy. The general plot of this novel was:

After Wang Fan transmigrated, he found an APP on his phone. There were many games in this APP, and as long as he cleared the game, he could get reward points, which could be exchanged for character cultivation techniques.
However, this was not the most important thing. As he cleared one game after another, he realized that his wife in the game was actually…
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"The Lord of the Empire" was a game novel written by the author, Odin Messenger. The general plot of the novel was:

In short, this was a story of a transmigrated player who used thirteen years of gaming experience to persevere and rebel.
To be more specific, the unlucky protagonist transmigrated into the game world and ended up possessing a poor man who was about to starve to death. In order to survive, he had no choice but to recruit people to rebel. As long as the hoe was swung well, there was no empire that could not be uprooted!