Official Sound

Official Sound


Release Information
Release GroundbreakinG -BOF2010 Compilation Album-, Parousia
Links GroundbreakinG, Bandcamp (Parousia)


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  • It's important to maintain stamina for the entirety of the chart, as it is very stamina-heavy. One way to mitigate this is to know where your hands should move in every section of the chart.
    • The arc section after the first chorus can be benefited to regain some of the stamina back.
  • Due to the repetitive nature of the chart in many sections, consistency is required.
  • Be careful of the triangle patterns in the middle of the chart, as it changes rotation in the middle.


Link Player Score Sounds
YouTube higllus 10,001,227 (MAX) Finger taps
YouTube StaLight 10,001,202 Finger taps
YouTube Ritxman 10,001,198 Fingernail taps
YouTube RenGE124 10,001,181 Finger taps
YouTube KONSOMEth 10,000,899 None


  • "Halcyon" is an English word, meaning "a past period of happiness remembered better than the present", "calm and peaceful", or "prosperous" [1]. It is also the name of a genus of kingfishers [2].
  • Halcyon was originally made for BOF2010. With 255406 points, it placed 1st overall, winning the event [3].
    • Halcyon has also appeared in Cytus, SOUND VOLTEX, Groove Coaster, CHUNITHM, Ongeki, STELLIGHTS, Muse Dash, TAPSONIC TOP/BOLD, maimai DX and SEVEN's CODE.
    • Due to the popularity in BOF2010 and appearances in popular rhythm games, Halcyon is one of xi's most well known songs, and has put xi as a composer on the map for many people.
  • Halcyon FTR is considered by most to be harder than Ether Strike FTR, a chart that is unlocked after clearing Halcyon FTR.
  • The chart designer's name 東星 is likely an alias of Toaster, since 東 can be read "tou" and 星 means "star."


  2. wikipedia:Halcyon_(genus)
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