New Xbox Game Pass tiers may be on the horizon, according to some recently surfaced evidence pulled directly from Microsoft's servers. The leak contains mentions of four codenames linked to unidentified xCloud programs, which could be related to one or more upcoming Xbox Game Pass membership plans.
Microsoft last restructured its popular subscription service back in September 2024. That's when Xbox Game Pass Standard and Core were introduced, offering access to reduced content catalogs and benefits for a smaller price. XGP Standard was an entirely new addition to the service, whereas Core was positioned as a direct replacement for Xbox Live Gold. Rumors of even more tiers being in the works have sporadically surfaced online ever since.
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Continuing this trend, some circumstantial evidence pointing to new Xbox Game Pass tiers has now emerged on social media, with Bluesky user Redphx uncovering references to four unidentified "program" names recognized by the Xbox Cloud Gaming API: Callisto, Dia, Europa, and Ferdinand. In this context, "programs" refer to xCloud offerings, of which only three are currently active: Xbox Game Pass Ultimate, a bring-your-own-game plan, and a limited free-to-play Xbox Cloud Gaming option that currently includes only Fortnite. These active programs are identified by name in the API, suggesting that the four newly discovered entries—being less descriptive—are likely codenames.
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Something is incoming to xCloud? Several games have been added to unknown programs called CALLISTO, DIA, EUROPA, and FERDINAND. - AC Origins - DOOM 64 - Genshin Impact - GTA V - Hellblade II - Psychonauts 1 & 2 - Retro Classics - TUNIC - Undertale - Unravel Two - Viva Pinata — red // Better xCloud (@redphx.com) 2025-07-23T00:07:58.921Z
The Best War Games was able to independently replicate these results by querying Microsoft’s undocumented but publicly accessible API. Whether the four codenames truly refer to some unannounced Xbox Game Pass tiers is debatable, but since their mentions were pulled directly from Microsoft's servers, there is no doubt about the authenticity of the monikers themselves. In other words, something code-named Ferdinand, Dia, Europa, and Callisto related to Xbox Cloud Gaming is indubitably in the works. Cloud-only Xbox Game Pass tiers are one possible interpretation of this leak, as such offerings were rumored to be under consideration since summer 2024.
Leaked Xbox Cloud Gaming Program Codenames
- Callisto
- Dia
- Europa
- Ferdinand
The xCloud API returns program references as an array of strings. Redphx speculates that their order implies tier hierarchy, with Callisto representing the highest and Ferdinand the lowest. However, because the array is clearly sorted alphabetically—and with the Xbox Game Pass Ultimate tier listed last—this interpretation remains questionable. If the order has any connection to the tier hierarchy, it's just as plausible that Ferdinand is the highest (non-Ultimate) tier and Callisto the lowest. Even if new Xbox Game Pass memberships are coming, not every single one of these leaked programs will necessarily map to a unique tier. After all, two of the three currently available programs (xCloud BYOG and Ultimate) are both linked to a single plan, XGP Ultimate.
Xbox Games Tagged As Supporting Newly Leaked xCloud Programs
|
Game |
Callisto |
Dia |
Europa |
Ferdinand |
|---|---|---|---|---|
|
Assassin's Creed Origins |
✅ |
✅ |
✅ |
❌ |
|
Doom 64 |
✅ |
✅ |
✅ |
✅ |
|
Genshin Impact |
✅ |
✅ |
✅ |
✅ |
|
Grand Theft Auto 5 |
✅ |
✅ |
❌ |
❌ |
|
Senua's Saga: Hellblade 2 |
✅ |
✅ |
✅ |
❌ |
|
Psychonauts |
✅ |
✅ |
✅ |
✅ |
|
Psychonauts 2 |
✅ |
✅ |
✅ |
✅ |
|
Retro Classics (Antstream) |
✅ |
✅ |
✅ |
✅ |
|
Tunic |
✅ |
✅ |
✅ |
❌ |
|
Undertale |
✅ |
✅ |
✅ |
❌ |
|
Unravel Two |
✅ |
❌ |
❌ |
❌ |
|
Viva Pinata |
✅ |
✅ |
✅ |
✅ |
As of July 23, at least 12 games have been rated as supporting one of these unannounced Xbox Cloud Gaming programs. Among them are Undertale, Doom 64, and Tunic, along with Viva Piñata, Assassin's Creed Origins, and Senua's Saga: Hellblade 2. GTA 5 also appears, though interestingly, only its Xbox One version lists compatibility. There's also one free-to-play game on the list, Genshin Impact, which is among only a handful of titles tagged as supporting all four of the unidentified programs.
