Screenshot by Abrar Al-Heeti/CNET

Back in 2010, Jeffrey Rosen and John Graham were developing a game called Overgrowth and wanted it to get noticed online. If that was ever going to happen, they needed to do something innovative.

"We wanted to come up with the craziest and best promotion we could think of," Graham said.

The result was Humble Bundle, a website that lets customers pay what they want for digital content such as ebooks and mobile games. Customers decide whether the money from their purchases goes to content creators, charity, the Humble Bundle team or a combination of the three.

In the company's first experiment, CEO Rosen and COO Graham launched the "Humble Indie Bundle," a collection of five indie games they hoped would bring in $100,000 in sales over an 11-day period. The bundle far exceeded their expectations, bringing in $1.27 million from 130,000 purchases.

The momentum has built ever since, with the company adding services such as Humble Monthly subscriptions ($12 a month) and the Humble Store, where users can buy individual games. Earlier this year, Humble Bundle launched a platform for publishing independent games.

The efforts have helped Humble Bundle raise more than $100 million for charities, including Action Against Hunger, the American Red Cross and the Electronic Frontier Foundation, the company said Friday.

"We'd like to make this $100 million for charity milestone look small," Graham said. "In not so long, hopefully we'll have another milestone to share."

Each month there's a featured charity on the Humble Bundle site. Sometimes it fits thematically with one of the games being offered (the World Land Trust, for instance, alongside a game about saving the rainforest). Other times, Humble Bundle's software partners suggest which charities should complement their content. Humble Bundle customers can also skip the featured charity and instead pick from a database of thousands of other philanthropic groups.

In addition to standard bundles, which are made available for a two-week period, Humble Bundle offers promotional collections tied to special events, such as gaming conference E3. It also creates bundles in response to crises and world events. One of Humble Bundle's most successful promotions was the Humble Freedom Bundle, a response to the Trump administration's immigration ban in January. Humble Bundle raised $6.7 million in one week for the American Civil Liberties Union, the International Rescue Committee and Doctors Without Borders.

"The whole gaming industry came together over that one because our customers are from all over the world, our employees are from all over the world, the game developers we work with are from all over the world," Graham said. "That was an issue that everyone wanted to weigh in on in a productive, positive way."

When customers make a purchase, sliders appear indicating where their money will go. By default, the site allocates 65 percent to content creators, 20 percent to Humble Bundle and 15 percent to charity, but customers can manipulate the sliders however they'd like. Graham said Humble Bundle doesn't publicly reveal where people choose to send their money because it doesn't want developers to compare their shares.

"People would drill into the data in a way that just wouldn't feel humble," Graham said. He added, "Often we find there's a bias towards charity, that if you want to manipulate the sliders, you're going to do so to lift the charity component."

Even with this freedom of choice, Humble Bundle has always received enough funds to keep it going.

Humble Bundle

"Especially when bundles were the only part of our business, the whole thing was growing and funded off of an optional, default tip," Graham said. "As long as people value our business and like what we do, hopefully they won't totally snub us all the time and in aggregate, we'll get enough to keep growing the business. And that's proven true."

Graham says customers come to the site because they want to find great content they can trust in an ever-noisier internet space. Developers, he said, aren't attracted only by the charity component, but also by the marketing value and by selling to customers they might not otherwise have reached.

Graham remembers going to E3 in the early days of Humble Bundle and having publishers ask, "What's a Humble Bumble? What do you guys do?" Within a few years, big publishers had not only learned how to correctly say the company's name, they also began asking how many promotions they could run that year.

Overgrowth, the game Rosen and Graham had planned to promote by launching Humble Bundle, is still in development. But one of their projects has already made an impact.

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