The latest code from the Xbox app for Windows 11 has revealed the unlock criteria for "Mythic Achievements": players may only need to earn all the base game's original achievements, without completing DLC or subsequent added achievements. This reward is seen as Xbox's equivalent response to PlayStation's Platinum Trophy system.
Xbox has not yet publicly introduced "Mythic Achievements" nor confirmed the specific requirements. However, the corresponding badge and unlock sound effect have already appeared in the latest version of the Xbox PC app, marking their first public appearance.
After analyzing the app content, XCT.live discovered that the system determines unlock conditions from an achievement group named "BaseGame." The prompt reads "Unlocked all N achievements in the original game," and the game page also provides a filter option for "Required for Mythic Achievement."
Items outside the base game achievement set are marked as "Additional Content," and DLC achievements do not count toward the "Mythic Achievement" unlock progress. According to the logic presented in the current code, even if a game adds more achievements after release, players may only need to complete all achievements originally included.
The code also indicates that this reward tracks the number of achievements rather than the corresponding Gamerscore. Therefore, "Mythic Achievements" do not require players to obtain the total Gamerscore available for a game; the criterion is based on whether all base game achievements have been unlocked.
It remains unclear when this feature will officially launch, and it is unconfirmed whether existing records from older games that meet the criteria can be retroactively unlocked. The final rules are still pending official announcement from Xbox.