This app automatically generates negative speed effects in osu!mania!

Paste the contents of an .osu file into the Input box. The app will generate a new difficulty where all timing points with Kiai Mode enabled are interpreted as negative speeds.

How often the screen "refreshes" during negative speed effects, in frames per second. Higher values look smoother but more glitchy. Default is 20.
The maximum distance from the judgement bar that notes can render during negative speed effects, measured by the number of milliseconds it would take to cover that distance at default speed. Higher values look more glitchy, but support lower scroll speeds. Default is 600.
How many chords (groups of notes with the same timestamp) can render at once. Higher values look more glitchy. Default is 4.
It can be inconvenient to test maps with negative speed effects because 1) you can't open them in the editor, and 2) you can't skip the intro. Use this setting to generate test difficulties where the provided number of milliseconds are cut from the start. Note: You will have to cut the audio accordingly!
When enabled, interprets 0.01x as a stop, 10.00x as a teleport, and 9.01x–9.99x as 10x–990x.



Feel free to contact me at Niv#3724 on Discord or Nivrad00 on osu! for bug fixes and feature requests. Source code is available here if you would like to make your own changes :)

Known limitations:

Check out this map for an example of what can be done using this tool:
The Breakbeat Junkie vs DJP - Hit me with the horns (Express Cut) [dragon.gif]