Microsoft’s Secret xCloud Codenames Hint at Game Pass's Future Expansion

A quiet storm is brewing in the world of cloud gaming. Over the past few days, sharp-eyed observers within the Xbox community have noticed something curious buried within Microsoft’s public APIs: four previously unseen xCloud program codenames—Callisto, Dia, Europa, and Ferdinand. First brought to wide attention by a Bluesky user named Redphx and subsequently reported on by outlets like Gamerant and Windows Report, this subtle leak is fueling speculation that Microsoft is preparing to expand or radically alter its Game Pass and xCloud offerings. While the company has yet to officially comment on these findings, a closer look reveals why the discovery could be a significant milestone for cloud gaming’s future, and how it may redefine Game Pass as we know it.

Discovery of the Codenames: What Do We Know?​

The four codenames—Callisto, Dia, Europa, and Ferdinand—first emerged after data enthusiasts dug into Microsoft’s publicly accessible APIs. According to reporting from Windows Report and corroborated elsewhere, these program identifiers were embedded in records that specifically referenced Xbox’s cloud gaming infrastructure. Crucially, these names do not match any known xCloud products or Game Pass subscription tiers presently available to consumers.
Currently, the xCloud family consists of three well-known branches:

• Xbox Game Pass Ultimate: The all-inclusive tier enabling streaming of Game Pass titles across devices.
• Bring Your Own Game (BYOG): An experimental feature allowing users to stream titles they own outside the standard Game Pass catalog.
• Fortnite-Only Free Tier: A cloud-based, cost-free option for playing Fortnite without a Game Pass subscription.

These new codenames, however, do not align with the above categories, suggesting that Microsoft is developing fresh tiers or feature sets for its streaming service. The company’s silence on the matter only adds to the intrigue.

Tracing the Evidence: Games Linked with the Codenames​

Digging deeper, enthusiasts noticed that at least a dozen notable titles in Microsoft’s API are tangentially associated with these new identifiers. Among the prominent games found linked to “Callisto”, “Dia”, “Europa”, and “Ferdinand” are:

• Assassin’s Creed Origins
• Hellblade 2
• Genshin Impact
• Undertale
• Grand Theft Auto V (Xbox One version)

The fact that marquee games spanning multiple genres and publishers are flagged in the API under these mysterious codenames lends credibility to the theory that these are not mere placeholders or abandoned test cases. Instead, the presence of both recent releases (Hellblade 2) and established classics (Undertale, GTA V) hints at a forward-looking initiative with broad appeal.

Microsoft’s Recent Game Pass Overhaul: A Relevant Backdrop​

To appreciate the significance of the new codenames, it’s important to recall Microsoft’s last major Game Pass update in late 2024. That shift saw the introduction of the “Game Pass Standard” tier, the transition of Xbox Live Gold into “Core,” and changes to how users access multiplayer features and the content library. In the months since, fans and analysts have speculated that further segmentation of Game Pass—especially around cloud-specific options—was imminent.
Given this context, the surfacing of new xCloud program names strengthens the case for an impending expansion or reorganization of Microsoft’s subscription ecosystem. Industry watchers—including those at GameRant and Verge-aligned forums—have long predicted that Game Pass would fragment into more granular, cloud-powered tiers to maximize reach and cater to an increasingly diverse global user base.

Deciphering the Codenames: A Mythological Motif​

There’s a pattern to the codenames themselves that is hard to ignore. Each moniker—Callisto, Dia, Europa, and Ferdinand—has a connection to astronomy and mythology. All are the names of moons orbiting Jupiter (with Callisto, Europa, and Dia being real celestial bodies, and Ferdinand a moon of Uranus). Naming conventions that draw from planetary satellites are not unusual at Microsoft (consider its tradition of codenaming Windows builds after famous places or mythological figures), suggesting that these projects are interrelated, if not thematically unified.
The mythological resonance may signal that these programs are intended as “satellite” offerings around the mainstay Game Pass product—a subtle hint at feature-rich, possibly experimental, cloud gaming experiences orbiting the core service.

Critical Analysis: Possible Motives and Directions​

Microsoft's refusal to comment on the leak leaves much to educated speculation. Still, by analyzing the tech giant’s recent business maneuvers, market positioning, and broader trends in subscription gaming, several plausible scenarios emerge.

Cloud-First Expansion​

With cloud gaming rapidly advancing—bolstered by improved server infrastructure and widespread 5G/6G adoption—Microsoft may be readying a tiered xCloud ecosystem. This could allow for:

• Platform-Agnostic Access: Enabling streaming on more non-Xbox hardware, perhaps including smart TVs, tablets, or even browser-based clients.
• “A La Carte” Subscriptions: Offering narrowly focused packages for specific franchises or genres. For example, a “Family Friendly” cloud tier or a “Day One Indies” collection.
• Regional Pricing and Content Variants: Adjusting content libraries and fees for different global markets, using new codenamed programs as test beds for localized offerings.

Expansion of BYOG and Cloud Publishing​

The recent appearance of major third-party titles (like Genshin Impact and GTA V) under the new program codes may reflect an attempt to scale the BYOG (Bring Your Own Game) concept. In practice, this could mean:

• Letting Players Stream Owned Titles: Beyond the Game Pass catalog, users could stream any game they own (digital or physical), vastly increasing xCloud’s utility.
• Developer-Led Cloud Ports: Publishers like Ubisoft or Rockstar could be granted flexibility to port their Game Pass or non-Game Pass titles to xCloud faster under these new frameworks.

Experimentation with Ad-Supported or Free Tiers​

Microsoft already runs a Fortnite-only free streaming tier, and its recent moves—such as Xbox’s partnership with Samsung smart TVs—suggest an appetite for broad, low-barrier cloud access. The new programs might signal:

• Ad-Supported Plans: Users stream select games for free or at a discount in exchange for periodic ads, akin to models seen on Peacock or Hulu.
• Event-Based or Time-Limited Access: For instance, free streaming weekends or special “pop-up” tiers for major game launches or esports events.

Risks and Caveats: What Could Go Wrong?​

While the leak is tantalizing, it’s worth considering the considerable risks and unanswered questions:

• Fragmentation Confusion: Introducing too many tiers or confusing feature sets could overwhelm users and erode Game Pass’s core value proposition: simplicity and abundance.
• Content Licensing Complexities: Getting third-party titles like GTA V or Genshin Impact to play ball with flexible cloud models is easier said than done, requiring complex negotiations and probably higher costs.
• Performance and Uptime: Rolling out cloud access to a broader audience increases pressure on Microsoft’s Azure infrastructure. Underperformance or outages could quickly sour public perception, especially if new tiers are perceived as unreliable.
• Market Cannibalization: If too many core titles become available through free or super-cheap tiers, it could cannibalize paid, premium subscriptions.

Broader Industry Implications​

The potential expansion of xCloud was always more a “when” than an “if.” Gaming subscriptions are evolving along the same lines as streaming video: increasing segmentation and customization. With Sony expanding PlayStation Plus and Nintendo quietly building out its own online platforms, Microsoft’s response appears to be a bold, cloud-centric play.
If the codenames represent new test programs rather than product launches, it reveals Microsoft’s commitment to experimentation at scale—a crucial advantage when trying to stay ahead in the cloud gaming arms race. Agile, data-driven pilots are easier to iterate or abandon if they fail to resonate.

What Comes Next? Speculation and Watch Points​

Given the amount of game data linked to these four mysterious identifiers, it is likely that Microsoft will move to formalize, announce, or quietly test new Game Pass or xCloud tiers in the near future. Recent changes to Game Pass and the company’s aggressive expansion into smart device partnerships lay the groundwork for something big.
Key indicators to watch in the coming months include:

• Beta or Insider Program Announcements: Microsoft frequently uses “preview” groups to test new Game Pass or xCloud features before formal rollout.
• Changes to the Xbox App UI: Look for new subscription options, filtering features, or hints about ad-supported streaming in the Xbox app or on web dashboards.
• Publisher Moves and Cloud-First Porting: If major studios begin referencing cloud streaming or launch “streaming enhanced” editions, Microsoft’s hand will be exposed.

Final Thoughts: Cloud Gaming’s Next Leap?​

The surfacing of Callisto, Dia, Europa, and Ferdinand in Microsoft’s own documentation feels less like a routine test and more like the overture to a much larger push into cloud gaming. Historically, leaks from Xbox’s API ecosystem have preceded significant commercial shifts—from Game Pass Core’s introduction to the arrival of Play Anywhere and Project xCloud itself.
While caution is warranted—public APIs often host experimental or deprecated programs, and leaks can occasionally mislead—the discovery is too widespread, consistent, and high-profile to dismiss as mere coincidence. If Microsoft executes well, the next round of xCloud innovation could make gaming truly device-agnostic, globally accessible, and tailored to more playstyles than ever before.
In this, Game Pass could finally cross the finish line from disruptive subscription to essential infrastructure; from platform to omnipresent, cloud-native service. The days to come will tell if Callisto, Dia, Europa, and Ferdinand become household names among gamers, or disappear as quietly as they surfaced, relics of experiments that shaped a more ambitious future. For now, all eyes are on Redmond, awaiting the next move in the cloud gaming chess match.

---

Source: Windows Report Four Mysterious xCloud Program Codenames Surface in Microsoft’s API Hinting at New Game Pass Tiers