Microsoft has confirmed that it is purchasing Swiss gaming company Mojang, which is best known for developing the worldwide success Minecraft, for $2.5 billion.

In an announcement posted on Monday, Microsoft's head of Xbox Phil Spencer said it was an "incredibly exciting day for our team" because Mojang and the whole Minecraft franchise were soon going to be part of Microsoft. Mojang also confirmed the acquisition in its own blog post, assuring the millions of Minecraft fans all over the world that Mojang and Minecraft will "continue to grow in an awesome way" under the helm of Microsoft.

When rumors first broke out last week that Microsoft was in advanced talks with Mojang for an acquisition, hoards of Minecraft players, most of whom belong to the kids and teens demographics, took to the web to express their displeasure. Minecraft player George Musser went on Twitter to ask the Mojang team if they "really care so little for users" after hearing the rumors. Others reminded Minecraft founder Markus Persson, who is lovingly called Notch in the gaming community and seen as a folk hero of sorts for his criticism of big technology corporations, that he promised not to sell Minecraft to big companies.

@notch You gave us your word you wouldn't sell out to big name companies. Please, Notch, don't let us Minecrafters down.

— D Malory (@dmalory) Sept. 11, 2014

The acquisition is expected to be completed by the end of the year, after which Persson, along with Mojang co-founder Jakob Porser and CEO Carl Manneh, will be leaving the company. Persson, whose Notch Development owns 71 percent of Mojang, explains in a blog post that he doesn't "make games with the intention of them becoming huge hits, and I don't try to change the world."

"Minecraft certainly became a huge hit, and people are telling me it's changed games," Persson writes. "I never meant for it to do either."

"I'm aware this goes against a lot of what I've said in public. I have no good response to that," he adds. "I'm also aware a lot of you were using me as a symbol of some perceived struggle. I'm not. I'm a person, and I'm right there struggling with you."

Minecraft players are worried that the acquisition would spell the end of Minecraft as they currently know and love. Several fans say Microsoft might restrict Minecraft to its own platforms instead of making it available on Windows, Xbox, PlayStation, Android and iOS as it is now. There is also the fear that Microsoft would stuff Minecraft full of in-app purchases. Right now, there is only one way Minecraft makes money for Mojang. Players buy a copy of the game on their preferred platform, and they can explore the Minecraft world and its updates for a lifetime.

A few fans, however, consoled themselves with the fact that a Microsoft acquisition means deeper pockets for game development, which could potentially open up new worlds for Minecraft gamers, as long as Microsoft keeps its hands off the actual development.

"Minecraft will continue to evolve, just like it has since the start of development," says Mojang. "We don't know specific plans for Minecraft's future yet, but we do know that everyone involved wants the community to grow and become even more amazing than it's ever been."

It's not clear how the Minecraft acquisition will fit into Microsoft CEO Satya Nadella's plans to push productivity as its focus, but he earlier acknowledged that "the single biggest digital life category, measured in both time and money spent, in a mobile-first world is gaming."

Speaking at the annual Seattle Metropolitan Chamber of Commerce on Monday, Nadella said Minecraft is a great asset that will boost the company's move into the education sector, saying that Minecraft's "open-world platform" makes it "the one game parents want their kids to play."

"If you talk about STEM (Science, Technology, Engineering and Mathematics) Education, the best way to introduce anyone to STEM or get their curiosity going on, it's Minecraft," Nadella said.