Huge huge spoilers. So the novel begins with MC being tasked with roles to play to accumulate points, and he falls in love with ML, a NPC. That's the foreshadowing and hint of the truth of The World.

Are you ready for the spoiler? MC is a beta-tester for ML's game called The World. The reason why he was on the leaderboard is because the game is still in a closed beta-testing period, so only the developers and some other beta-testers played it. ML is on the top of the leaderboard because he cleared many more worlds, which makes sense because as the creator he's making sure it works/checking for bugs. Additionally, the taskers are allowed to make some changes to the script because the game is intended to have multiple endings as a result of the players actions. ML and MC were friends in high school who grew apart and ML had an unrequited love for MC. Somehow they ended up in the same city as adults (it's implied that ML followed MC when he grew up, revealed by his colleague at the company who was MC's roommate in college and witnessed ML looking at MC's picture on the bulletin board). ML was the one who approved MC to be a beta-tester and he entered his own game as a NPC to interact with MC, but his memories were sealed and he couldn't help falling in love again and again.

• • Arc 1: The Cannon Fodder Roommate of the Unlimited Flow Male Lead

• • Arc 2: The Unwed Wife of the Favored Son of Heaven

• • Arc 3: The Vicious Ex-Boyfriend of the Impoverished Bigshot

• • Arc 4: The Beloved Control Group in a World of Civilization Discontinuity

• • Arc 5: Humanoid Disaster Demolition Defender

• • Arc 6: The League Support Suppressed by Teammates

• • Arc 7: The Unparalleled Civil Official in a Chaotic Era

• • Arc 8: The Heir's Little Follower

• • Arc 9: The Otherworldly Friend of the Main Protagonist in the Comic Book World

• • Arc 10: My Rare and Unattainable Encounters

All MLs are the same person, he's playing different NPCs

Arc 1: The Cannon Fodder Roommate of the Unlimited Flow Male Lead

• • ML's name: Su Huai, the OP protagonist

• • Well-written, I actually forgot MC was a QT mission tasker and felt that the unlimited flow could have been a standalone novel if there were more than two dungeons (two arcs), however it does a good job for setting the tone for the novel as we discover MC will save people when he can even if it's "OOC".

• • MC also told ML he would always be able to recognize him, since their faces change in the dungeons, and then... MC is able to recognize ML in every world LOL.

Arc 2: The Unwed Wife of the Favored Son of Heaven

• • ML's name: Xie Yibai, the long aotian

• • One of my favourite arcs with a wholesome ending

Arc 3: The Vicious Ex-Boyfriend of the Impoverished Bigshot

• • ML's name: Shen Zhou, the talented businessman

Arc 4: The Beloved Control Group in a World of Civilization Discontinuity

• • ML: Sa Yin, grumpy merman king

• • MC teaches ML how to grill meat over a fire... he will subconsciously remember how to grill meat in Arc 8 LOL

• • My fav part about this arc is the baby panda running up to hug MC:"Master." A little panda ran up with tears streaming down its face, stuffing its soft ears into Yu Lin's hand. Yu Lin raised his hand and gently rubbed them.
    

    Yu Lin held a high official position, and the cubs both respected and loved him. When their ears were touched, they would stand up shyly and then complain, "Some bad guy is trying to steal you!"

    A group of furry creatures stretched out their paws and pointed at the bad fish standing against the wall at the entrance of the daycare center.

    Sa Yin crossed his arms and snorted disdainfully at the scene, not taking the brats seriously.

Arc 5: Humanoid Disaster Demolition Defender

• • ML: Yu Zhou, aka "White Bird" the most dangerous humanoid calamity

• • One of my favourite arcs and I love the humor

Arc 6: The League Support Suppressed by Teammates

• • ML: Zhuang Ningyu, captain of Dawn

• • eSports theme

Arc 7: The Unparalleled Civil Official in a Chaotic Era

• • ML: Wei Zhiji, noble destined to be the King of Wei in chaotic times and lead a new dynasty

• • Another favourite arc, because MC and ML saved many people

Arc 8: The Heir's Little Follower

• • ML: Zhao Yanjing, the heir of the most powerful and affluent family

• • MC did a good job acting ambitious (and using cuteness to get his way) so people thought he was scared into shock from saving ML from a bullet when really he just wanted to relax and not work so hard LOL

• • I suspect ML's mom in this world is the real world's ML's mom's name?

Arc 9: The Otherworldly Friend of the Main Protagonist in the Comic Book World

• • ML: Xu Zhouyan, the hero of a another world, connected to MC who is the protagonist of a comic book in his world

• • Honestly I loved the beginning to this story, it was so cute when ML thought to himself he'd finish the green pepper and shredded pork with rice dish that MC bought but didn't enjoy, and then suddenly MC's half-eaten dish appears in front of him and MC in the comic book is confused his food disappeared LOL this led to them sending each other notes and MC sending ML food. Sooo cute!

• • This world nicely connected to the real-world, because MC felt that the plot is very familiar and realized it's just like the comic he used to doodle on his desk as a high-school student. He vaguely remembers a friend he had who makes him feel comfortable just like the male lead...

Arc 10: My Rare and Unattainable Encounters

• • We find out ML's real name :)

• • We find out their shared past, and MC had no idea ML loved him so deeply, and the circumstances that led them to drift apart.

• • Everyone loved MC, and he's the type who would help other students. People recognize his kind and gentle personality, and his classmates would encourage him to continue the series of the comic he casually doodles on his desk. We find out MC enjoys stories about heroes saving the world

• • However, MC moved away, experienced hardships and was forced to grow up leading to him having a more quiet demeanor:

Ten years ago, Yu Lin was sunny and cheerful, the little sun of the grade. Ten years later, Yu Lin is a bit more aloof, quiet like a handful of moonlight falling in the middle of the night.

- From chapter 100

• • ML told MC that he never stopped loving him. His confession 10 years late is soooo romantic:

"You bumped into my arms at that time. Before that, I had never liked anything, whether it was a person, thing, or object. I seemed to be born indifferent. Your appearance made me realize what liking is.

I've passed by you many times until I got to know you. The more I learn about you each day, the more I like you. I'm like a robot whose program has been activated. Because of you, this program has started running.

I can't give up this feeling of liking you, I can't give you up. I gradually understood what it feels like to truly like someone, and every day after that, I felt very happy.

I once truly loved a wonderful person, even though he didn't know it. I still consider it a precious and lucky thing, but I just happen to be stubborn and unwilling to change.

Later... we met again. In the game world, I had no memory, but no matter how many times I saw you, I still couldn't help being attracted to you and falling in love with you."