Evidence uncovered from Microsoft's servers hints at potential new subscription tiers for Xbox Game Pass, specifically designed for cloud gaming. The discovery includes four codenames—Callisto, Dia, Europa, and Ferdinand—linked to unannounced xCloud programs, sparking speculation about future membership options.

Microsoft last revamped its subscription service in September 2024, introducing Xbox Game Pass Standard and Core. While Standard was a fresh addition, Core replaced the longstanding Xbox Live Gold. Since then, rumors have circulated about further tier expansions, and this latest leak adds credibility to those claims.

The leak originated from social media, where a user identified references to these four codenames within the Xbox Cloud Gaming API. Currently, only three xCloud programs are active: Xbox Game Pass Ultimate, a bring-your-own-game option, and a free-to-play plan limited to Fortnite. The discovery of four additional, unnamed programs suggests Microsoft is testing new cloud-exclusive tiers.

Possible Cloud-Only Xbox Game Pass Tiers

"Something is incoming to xCloud? Several games have been added to unknown programs called CALLISTO, DIA, EUROPA, and FERDINAND." — Redphx on Bluesky

Independent verification confirmed these codenames are indeed present in Microsoft's API, though their exact purpose remains unclear. One plausible theory is that they represent cloud-only subscription tiers, an idea Microsoft has reportedly explored since mid-2024.

Leaked Xbox Cloud Gaming Program Codenames

• Callisto
• Dia
• Europa
• Ferdinand

The API lists these programs alphabetically, making it difficult to determine their hierarchy. While some speculate Callisto could be the highest tier, the alphabetical order complicates this interpretation. It's also possible not all codenames correspond to distinct tiers—similar to how Ultimate currently encompasses multiple xCloud programs.

Games Linked to the New Programs

As of July 23, at least 12 games are tagged with support for these unannounced programs, including:

Notably, Genshin Impact is one of the few titles compatible with all four programs, while GTA 5 only lists support for its Xbox One version. The inclusion of free-to-play and retro titles suggests Microsoft may be diversifying its cloud offerings.

Latest Game Information

While Microsoft has yet to confirm these findings, the evidence points to an evolving Xbox Game Pass ecosystem, with cloud gaming likely playing a central role in future subscription plans.