YouTube Star makes how much?

                  Felix Kjellberg aka PewDiePie has almost 30 million subscribers on his  YouTube channel. He says he avoids the spotlight and even claims to be  uncomfortable with success, but has decided to share his thoughts on  fame and (computer) games with the WSJ. Photo: Ellen Jervell

STOCKHOLM— Felix Kjellberg doesn't play a very convincing mega star. The seemingly modest Swede avoids the spotlight, has no entourage and is uncomfortable with success.

But put Mr. Kjellberg in front of a Web-camera and he transforms into PewDiePie, by far YouTube's biggest draw. He has built a base of 27 million subscribers using a decidedly unorthodox approach to playing video and mobile games.

His videos aren't traditional game reviews. "Pewds," as he is often called, simply plays games and allows his audience—mostly teenagers—to peer in on his experience and hear random opinions interspersed with odd behavior. He contorts, screeches, swears, sings and even "twerks" to portray his feelings.

The 24-year-old Mr. Kjellberg, who created PewDiePie five years ago, has parlayed his persona into a brand name that pulls in the equivalent of $4 million in ad sales a year, most of it pure profit. In December 2012, PewDiePie signed on with Maker Studios, a producer of online content that takes a cut of ad sales. Maker Studios—which counts on PewDiePie as its most important personality—sold itself to Walt Disney Co. DIS -0.48% earlier this year in a deal that could be worth close to $1 billion, depending on certain performance targets.

His following is so big that even games he criticizes get coveted publicity.

Earlier this year, he made a clip headlined "Flappy Bird—Don't Play This Game," in which he curses a blue streak while he tries to conquer the then-unknown mobile app. Before long, millions of people had downloaded the game. It helped propel "Flappy Bird" and its Vietnamese developer from obscurity into a world-wide sensation.

Mr. Kjellberg also is inadvertently helping to shape the industry, as developers have started making games that aren't just fun to play, but also to watch others play on YouTube, like indie horror games.

"It's cool to have this kind of influence, but at the same time it's kind of scary," said Mr. Kjellberg, speaking in a rare interview. He routinely turns down media requests, citing a busy schedule that includes publishing multiple clips a day of himself playing obscure games from an apartment south of London.

While his subscriber base creates unparalleled reach on Google Inc. GOOGL -0.69% 's YouTube, his success reflects broader momentum for the trend in watching other people play videogames.

One of his peers is Jordan Maron, a 22-year-old American known as "Captain Sparklez" who has attracted 7.5 million subscribers with videos related to Mojang's popular Minecraft building-block game.

Production quality isn't a key selling point.

Mr. Kjellberg's creation process is quick, dirty and done mostly solo.

"Unlike many professionally produced shows, I think I've established a much closer contact with my viewers, breaking the wall between the viewer and what's behind the screen," he said. "What I and other YouTubers do is a very different thing, it's almost like hanging around and watching your pal play games. My fans care in a different way about what they are watching."

YouTube is playing a more integral role in the experience of gamers. Last week, Sony Corp. 6758.TO -0.67% announced an update to PlayStation 4 that integrates the online video service into the console so clips of game play can be easily shared.

Mr. Kjellberg's career took flight while attending college in Gothenburg, on Sweden's southwest coast. He attended few classes, spending more time at home playing games and uploading to YouTube. After dropping out, he started selling hot dogs. To pad the number of views on his channel during those early days he would repeatedly hit F5 on his keyboard to refresh the browser.

As for the name PewDiePie, he said that his original YouTube account was for PewDie—"pew" to sound like a laser gun, and die for death—but he lost the password and had to create a new account under a new name, so he added Pie.

With growth comes a level of attention that makes Mr. Kjellberg uncomfortable.

"I'm so central to YouTube now, and that puts me in the spotlight and raises a lot of questions like 'Why is he so big?'" he said. "I'd much rather prefer to have something like 5 million subscribers."

Kevin Lin, the chief operating officer of San Francisco-based Twitch TV—an online community for videogamers with live streams of game competitions— said PewDiePie's "strong personality and unique character" helped him achieve a level of success that is hard to crack in traditional forms of media.

PewDiePie's ability to draw viewers is valuable to game developers, said Anton Westbergh, chief executive of Sweden's Coffee Stain Studios AB. Coffee Stain developed "Goat Simulator," a game that is wildly popular and profitable, but unpolished and buggy.

Mr. Westbergh jokingly describes it as "the world's dumbest game." But PewDiePie's willingness to make videos about Goat Simulator legitimized its existence.

"Having guys like PewDiePie playing our game has been tremendous marketing," Mr. Westbergh said. "And for us, there have been no costs involved."

PewDiePie's foul language and silly antics can be confusing or offensive to the uninitiated. Mr. Kjellberg said, "I just let go and have fun."

Jens Orjeheim, 44, has an 11-year-old son who is a big fan of PewDiePie, but he fails to appreciate the appeal. "I think there are things in society that can be seen as contributing to a positive development," he said. "PewDiePie isn't one of them." He is critical of the fact that Mr. Kjellberg makes money from encouraging kids to spend more time in front of screens and elevating the importance of videogames.

But Vigor Sörman, founder of a YouTubers network in Sweden, said, "PewDiePie is like a cool friend you have and subscribing to him is almost like Skypeing with him—that's why viewers are such dedicated fans."