Screen-Shot-2015-05-08-at-9.02.26-AMMinecraft is one of the most successful video games in the world, with more than 100 million registered users. YouTube is the top video site in the world, with a billion unique visitors a month.

And when combined, they are a staple of today’s tween entertainment diet.

YouTube videos about Minecraft are giant hits, even though the game’s blocky graphics don’t seem to scream excitement. Millions of people watch players narrate while they fly, hike and excavate Minecraft’s virtual world, which is akin to an open world digital Lego set. The Minecraft narrators – often men in their early 20s with effervescent personalities – act as solo tour guides as they build skyscrapers, ships and other structures or engage in battles of survival.

The most popular narrators turn up the entertainment value by bantering with others in the style of a talk-show host. Still, the popularity of this genre can be slightly baffling. After all, children can play Minecraft — why watch others do it?

“It’s super bizarre,” said Mitchell Hughes, 21, a top Minecraft YouTuber who, like his peers in the streaming world, is far better known by his online handle, BajanCanadian. “I don’t even understand it myself.

From Minecraft’s earliest days, the company behind it encouraged people to share video clips on YouTube and other social media sites, seeing it as a potent form of grass-roots marketing. Initially, many of the Minecraft clips were tutorials for newbies to the game. They gradually evolved into their own genre of entertainment — a remix of Saturday morning cartoons, pop culture parodies and pranks.

The videos aren’t exactly “Mad Men,” but they aren’t trying to be ambitious television, either. As with a lot of reality television programming, much of the appeal lies in the emotions of the Minecraft narrators. When one squeals in terror, it seems authentic, whether it is or not.

“I think content beauty is in the eye of the beholder,” said Ryan Wyatt, the global head of content for gaming at YouTube.

YouTube, which is owned by Google, says Minecraft is the most popular game of all time on the site, ahead of Grand Theft Auto and Call of Duty, two major video game franchises. Last year, “Minecraft” was the second most searched term on YouTube, after “Frozen.” The popularity of the game explains why Microsoft paid $2.5 billion last year to acquire Mojang, the Swedish company that created Minecraft in 2009.

“The amazing thing about using this software is you can produce an amazing video every day with big production values,” said Joseph Garrett, a master of the Minecraft YouTube genre who uses the handle Stampy. “If you were doing live action shows that could be done, but it wouldn’t be as easy.”

Mr. Garrett has more than 5.7 million subscribers to his Stampy videos, which have been seen almost 3.5 billion times, placing him just ahead of Lady Gaga in terms of cumulative views. BajanCanadian has 4.8 million subscribers on YouTube and, since he joined the service in 2011, his videos have been watched more than 1.2 billion times.

YouTube has become a lucrative, full-time career for Mr. Hughes and Mr. Garrett, who get a cut of advertising revenue from their videos. Neither would say how much they make — “Billions!” joked Mr. Hughes — but both are making a healthy living off the videos.

Based on publicly available audience numbers and typical advertising rates, Peter Warman, an analyst with the market research firm Newzoo, estimates there are eight to 10 Minecraft YouTubers who earn over $1 million a year.

To get a better grasp on what it takes to be a successful Minecraft YouTuber — and, by extension, better understand what makes the videos so popular — I enlisted the help of YouTube itself, Mr. Hughes and Mr. Garrett. Although the alchemy behind online sensations is as elusive as for any other kind of celebrity, they all shared some basic prerequisites for their stardom.

Have personality, a lot of it

All the top Minecraft YouTubers are extroverts, or at least act like them in the voice-overs for their videos. Mr. Garrett’s Stampy is like a British version of Mr. Rogers after inhaling a bit of helium. As he gambols around a Minecraft map of his own creation, a cluster of buildings, tunnels and landscapes he calls “my lovely world,” Stampy seems to exist in a permanent state of delight.

“It’s a bigger, brighter version of me,” said Mr. Garrett, a former bartender who records his shows from his home in southern England. (To deter stalkers, he won’t give precise details about where he lives.)

The videos on his main YouTube channel are nonscripted, lasting around 20 minutes each. While plenty of Minecraft YouTubers delve into off-color humor, Mr. Garrett, represented in the game as a yellow-and-white cat, keeps his videos clean and cheerful.

“I would never get angry in a video,” he said. “If I lose, it’s, ‘Oh well, maybe next time I’ll do better.’ Everything is positive and happy. It’s the ideal me, living in the ideal world, where nothing ever goes wrong.”

Collaborate with others

Mr. Hughes believes a big reason his videos as BajanCanadian have been so successful is that he records himself playing with friends. Most of the videos consist of Mr. Hughes and a couple of friends exchanging jokes as they play survival games with other online players.

The fraternal chemistry between Mr. Hughes and his buddies seems genuine and keeps his videos from growing dull. Mr. Hughes’s roommate in St. Petersburg, Fla., Jerome Aceti, is a childhood friend with his own large YouTube following under the online name JeromeASF. He makes frequent cameos in BajanCanadian videos.

“Definitely surround yourself with positive influences and friends who are going to be able to motivate and participate in your content,” Mr. Hughes said. “Otherwise it might get lonely. That makes it a lot more fun.”

Some Minecraft YouTube stars, like Mr. Garrett, are mostly solo artists. But even that’s changing with a new Stampy side project called Wonder Quest that Mr. Garrett is creating in partnership with YouTube and Maker Studios, a producer of short online videos owned by Walt Disney. The scripted series has a cast of other YouTubers who voice various characters.

Be consistent

Mr. Wyatt of YouTube said any aspiring YouTube star seeking to build an audience should release new videos on a dependable schedule. Die-hard fans will come to expect fresh episodes, and they will be disappointed if the videos don’t appear.

“Often people get demoralized or complacent and stop doing consistent programming,” Mr. Wyatt said. “Whatever your schedule is, stay consistent to it.”

Mr. Hughes and Mr. Garrett post new videos at least once a day, sometimes multiple times a day. Mr. Garrett says keeping up that pace can be challenging, but it has been worth it.

“My fans love it,” he said. “Most content creators are creating one video every two weeks. I choose to be a little more programmatic about it. That was a big steppingstone for me.”

Minecraft Stars on YouTube Share Secrets to Their Celebrity