Xbox Game Pass has seen its fair share of evolution lately, but if a newly surfaced leak holds any truth, Microsoft may be gearing up for another shakeup. A user on Bluesky, going by the name Redphx (via Gamerant), has discovered four new xCloud program codenames buried in Microsoft’s publicly accessible API, and they might hint at the arrival of new Xbox Game Pass tiers.
Spotted in the wild: Callisto, Dia, Europa, and Ferdinand
The unused program names — Callisto, Dia, Europa, and Ferdinand — were identified through Microsoft’s xCloud Gaming API. While the current system features only three known xCloud programs — Xbox Game Pass Ultimate, a bring-your-own-game (BYOG) plan, and a free-to-play tier exclusive to Fortnite — these new names don’t correspond to any of them.
Unlike the active programs, which are clearly labeled in the API, these new entries are coded vaguely, suggesting they’re development placeholders or internal codenames for upcoming offerings. Since this data comes directly from Microsoft’s servers, the authenticity of the leak isn’t in question; what remains a mystery is what, exactly, these programs mean for the future of Game Pass.
A Refresher: The Xbox Game Pass restructure of 2024
\The last major overhaul came in September 2024, when Microsoft introduced Xbox Game Pass Standard and Xbox Game Pass Core. The former was a fresh addition, aimed at offering a more budget-friendly middle-ground, while the latter replaced the long-standing Xbox Live Gold. Ever since that move, rumours have been flying about even further tier diversification, and this latest find seems to feed that fire.
Are cloud-only tiers the next frontier?
One possible explanation? These new programs could signal cloud-only Xbox Game Pass tiers. Speculation has circulated about such offerings since mid-2024, and this leak aligns well with those rumours. Especially considering xCloud is becoming an increasingly core component of Microsoft’s gaming ecosystem.
Game Rant confirmed the findings by querying the same API endpoints, an extra layer of validation that helps elevate this from pure rumour territory.
Decoding the tier rankings: Fact or Fiction?
There’s some debate around the order of these leaked programs. Redphx theorises that the order might correlate to a tier hierarchy, potentially placing Callisto at the top, and Ferdinand at the bottom. But here’s the catch: the API seems to sort programs alphabetically, and notably places Game Pass Ultimate — arguably the highest-tier option — last in the list. So that theory? We’re taking it with a grain of salt.
Another plausible idea is that some of these programs might tie back to the same plan. As seen in the current setup, both BYOG and Ultimate are linked to XGP Ultimate, which suggests multi-program connections to a singular tier are very much on the table.
Games already flagged for the mystery tiers
Here’s where things get even more interesting: at least 12 games have already been tagged in the API as supporting one or more of these mysterious programs. Here’s a sample of the games involved:
- Assassin’s Creed Origins
- Callisto, Dia, Europa
- Doom 64
- Callisto, Dia, Europa, Ferdinand
- Genshin Impact
- Callisto, Dia, Europa, Ferdinand
- GTA V
- Callisto, Dia
- Hellblade 2
- Callisto, Dia, Europa
- Psychonauts
- Callisto, Dia, Europa, Ferdinand
- Undertale
- Callisto, Dia, Europa
- Viva Pinata
- Callisto, Dia, Europa, Ferdinand
Games like Undertale, Doom 64, Genshin Impact, and Tunic are all flagged, while even next-gen headliners like Hellblade 2 are present. Notably, GTA V’s Xbox One edition appears, but not its Series X|S version, maybe a pointer toward tier-specific compatibility or legacy support.
We’re still in wait-and-see territory here. These leaked names could map to new subscription plans, experimental feature sets, or internal testing environments. But considering how seamless Game Pass integration has become across Xbox and PC, it wouldn’t be far-fetched to see tiered cloud access, exclusive xCloud features, or regional pricing models roll out under new branding.
Whatever the case, it’s safe to bet that major developments for Xbox Game Pass are on the roadmap. And remember: cloud gaming isn’t just some side hustle for Microsoft anymore: it’s baked into the entire ecosystem. These leaks might just be the start of a new phase.
We’ll keep eyes on the API and ears to the ground. Until then, grab your controllers and boot up Game Pass: it may start looking very different, very soon.