Xbox Mythic Achievements roll out to Insiders and are awarded retroactively as far back as Xbox 360 games

Microsoft has officially announced Xbox Mythic Achievements, the equivalent of PlayStation's Platinum Trophies, and they are rolling out to Xbox Insiders now. Mythics are earned by unlocking all other Achievements in a game, are unaffected by add-on Achievements added after release, and are awarded retroactively as far back as Xbox 360 games. They arrive alongside an Achievement tidy-up that adds a Gaming tab to profiles; no date has been given for a full rollout, and players can join the Xbox Insider Program via the Xbox Insider Hub.