Song order

Songs are sorted for each difficulty by level, in ascending order. When two songs have the same level, a custom complexity index (Ω) is used to determine which one should be first.

Complexity index (Ω)

Each note or hold note start event, adds:

(1 - subdivision) * (isJump ? 2 : 1) * (isHold ? 1.3 : 1)
         ^             ^ if it has two or more arrows
         ^ e.g. 1/4 for quarter notes

Then, the sum is divided by the length of the song in seconds.