- April Fools' Day 2018
- Tap several times on the "GRIEVOUS RANDOM" button in the end of the song list.
- April Fools' Day 2019 onwards
- Tap several times on the "Like" (heart) icon of Ignotus.
- Ignotus Afterburn is a remix of several songs in Arcaea, and is only available on April Fools' Day since 2018. The songs are:
- April Fools' songs have several idiosyncrasies:
- Future only: no Past and Present difficulties.
- Undefined difficulty level: the Future chart difficulty is just written as "?".
- Undefined chart constant: playing this song has no effect on Potential.
- Camera feature: notes can be outside the usual input boundaries.
- "Arcaea Sound Team" is a reference to the naming of "BEMANI Sound Team" in KONAMI's BEMANI rhythm game series. The Future chart's style refers to KONAMI's rhythm game SOUND VOLTEX, including various track movements and unique arcs.
- It was later revealed that nitro is the composer of the song .
- In nitro's official soundtrack on SoundCloud, the song is titled "ignotus -afterburn-".
- A direct sequel to this song was hinted at, but this was a red herring.
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