Scroll speed multiplier: Instead of a constant number like what Kade Engine has, a scroll speed multiplier would take the value from each chart and multiply it by a given value. This would probably be more compatible with the idea below.
Slider Velocity (SV): A common form of modcharting that alters the scroll speed of the song mid-chart. There are good examples of this type of modchart dating back to early 2000s DDR at its roots. This is related to the other idea so I thought I'd put both in one issue.