CARY – Microsoft has joined Epic Games as an ally in the Cary-based video game technology firm’s legal dispute with Apple.

Xbox head Phil Spencer said in a tweet Sunday: “Ensuring that Epic has access to the latest Apple technology is the right thing for [game] developers and gamers.”

While the initial fight centered on Epic’s globally popular Fortnite and the right to sell in-app accessories without having to pay 30% fees to Apple and Google, the dispute has expanded to include Epic’s powerful and popular Unreal game development engine. Unreal is used for multiple types of projects, such as CGI effects with Epic receiving licensing fees.

Kevin Gammill, Microsoft general manager for Gaming Developer Experiences, said in a declaration filed with the court hearing Epic’s appeal for a restraining order to keep Apple from barring Epic from its iOS and App Store:

“If Unreal Engine cannot support games for iOS or macOS, Microsoft would be required to choose between abandoning its customers and potential customers on the iOS and macOS platforms or choosing a different game engine when preparing to develop new games …

“Apple’s discontinuation of Epic’s ability to develop and support Unreal Engine for iOS or macOS will harm game creators and gamers.”

Microsoft and Xbox also publish Gears of War, a former Epic Games franchise.

While there are alternative gaming engines, Gammill said that “very few” are available with as many features and the same functionality.

A hearing is set for Monday afternoon at the U.S. District Court for the Northern District of California.

Epic, which also has sued Google, says customers are expressing concerns about what Apple’s actions could mean.

CNBC noted that Nicholas Penwarden, Epic’s vice president of engineering, said Sunday that the company “has received ‘numerous inquiries and expressions of concern’ from companies to which it has licensed the Unreal Engine, including at least one business that does automotive design.”

On Friday, Epic CEO Tim Sweeney said Apple was being misleading about communications he had with the company about the App Store fee structure.

In a court filing Friday Apple said Sweeney had written its executives seeking a special deal on the fees. Epic is suing both Apple and Google after the internet giants moved to ban Epic and its megahit Fortnite from its stores when Epic moved to avoid the fees which are charged on in-app purchases.

“Apple’s statement is misleading,” Sweeney tweeted Friday.

“You can read my email in Apple’s filing, which is publicly available. I specifically said in Epic’s request to the Apple execs, “We hope that Apple will also make these options equally available to all iOS developers…”

In its filing, Apple noted the letter:

“On June 30, 2020, Epic’s CEO Tim Sweeney wrote my colleagues and me an email asking for a ‘side letter’ from Apple that would create a special deal for only Epic that would fundamentally change the way in which Epic offers apps on Apple’s iOS platform,” former Apple Senior Vice President Phil Schiller wrote in a declaration. Schiller, whose title is now Fellow, runs Apple’s App Store.”

Epic CEO says Apple is ‘misleading’ in response to lawsuit over app store