Microsoft has inserted itself into the ongoing legal dispute between Apple and Epic Games, and the Xbox company is lining up behind the Unreal Engine.

Unreal, which is Epic’s creation, is a set of software tools (often referred to as an “engine”) that developers use to build video games. Epic confirmed on Monday that Apple will cut the company off from iOS and MacOS development tools on Aug. 28. That spurred a response from Microsoft.

On Sunday, Microsoft filed a statement with the U.S. District Court in Oakland, Calif. claiming that Apple’s move to cut off Epic threatens a sizable community of creators that have no connection to the ongoing litigation.

“Denying Epic access to Apple’s SDK and other development tools will prevent Epic from supporting Unreal Engine on iOS and macOS, and will place Unreal Engine and those game creators that have built, are building, and may build games on it at a substantial disadvantage,” the statement from Microsoft exec Kevin Gammill reads.

“Because iOS is a large and growing market for games, Apple’s discontinuation of Unreal Engine’s ability to support iOS will be a material disadvantage for the Unreal Engine in future decisions by Microsoft and other game creators as to the choice of an engine for new games,” he added in a subsequent section. 

(For anyone who doesn’t know, Phil Spencer is the boss of all things Xbox at Microsoft.)

Microsoft’s move puts the company in the middle of a legal dispute that has spiraled out of control. Remember, this all started on Aug. 13 when Apple and Google, in twin moves, removed Epic’s hit game Fortnite from their respective official app stores. (A bigger problem for Apple users, since Android doesn’t lock people into using just the Play Store.)

The removals followed Epic’s introduction of a new way for players to purchase Fortnite‘s in-game currency, V-Bucks, at a reduced price. This new buying option allowed players to bypass in-app purchases, in turn depriving Apple and Google of the 30 percent cut they take from their respective app store sales.

Apple and Google both said Fortnite‘s removal from their app stores happened because Epic violated store policies. Step past the discount V-Bucks-as-protest action and weird radicalizing of Fortnite fans on Epic’s part, and this is a money dispute between multi-billion dollar companies. 

Epic is tired of cutting Apple and Google in on micro-purchases for its wildly successful game. The discounted V-Bucks option is just as much about pushing the platform gatekeepers to respond as it is about giving fans more incentive to spend money inside Fortnite.

The whole thing became significantly more complicated, however, the moment Apple escalated its response by cutting Epic off from iOS and MacOS development tools. Putting Fortnite aside, Epic’s Unreal Engine is an industry standard. It’s one of the most widely used creation tools in game development, spanning PC, console, and mobile game creation.

That’s no doubt a big piece of what spurred Microsoft to step in. Its own mobile game Forza Street is built on a modified version of Unreal, and the newly filed statement asserts that Apple’s move to cut Epic off – which effectively means no more app updates for content, functionality, or security purposes – puts that game, among others, at risk.

But there’s also another wrinkle here. Microsoft recently had its own showdown with Apple, after news emerged that the Xbox game-streaming platform xCloud wouldn’t be available on iOS devices. The reason? Apple said it violated store policies.

“Before they go on our store, all apps are reviewed against the same set of guidelines that are intended to protect customers and provide a fair and level playing field to developers,” the statement from earlier in August read.

That explanation didn’t go over well. Plenty of observers were quick to point out that Apple regularly allows platform-based software into the App Store without requiring approval on each specific piece of content contained therein. The speculation held, then, that Apple’s issue was with game platforms in the store, since games are the most popular product category in the App Store.

Apple’s resistance to competition from the likes of Xbox/xCloud and Google’s Stadia, which is also not in the App Store, is also probably part of the reason Microsoft made this very high-profile entry into the ongoing Apple/Epic fracas (though the statement makes no mention of xCloud). And while the core dispute doesn’t really threaten to impact most fans of video games, Microsoft is correct that Apple’s move to cut off Epic presents a risk to the entire industry.