''Avoid using combo colours with ~220 luminosity or higher during kiai times. They create bright pulses which can be unpleasant to the eyes.''
It is worded like so.
Now while changing slider track colouring isn't something that is seen often it is still a feature that mappers use from time to time and considering slider tracks also flash creating bright pulses during kiai times I feel like it would be a nice thing to specify as well that using a slider track colour with ~220 luminosity or higher also shouldn't be okay.
Since mappers can change slider tracks that don't match combo colours they used in the editor itself.
The reason why I decided to write this was because slider tracks are bigger than slider heads/tails which means that during kiai times most of the flashing comes from the slider track as you can see in the example below:
(thank you M a r v o l l o)
My suggestion is for this part of the guideline to be rewritten into something like:
''Avoid using combo colours and custom slider track colours with ~220 luminosity or higher during kiai times. They create bright pulses which can be unpleasant to the eyes.''
While not being a huge change in wording I do feel like it's a necessary thing to include.
To give an example for people not familiar with the terms or the feature:
Taken from this map
these are the combo colors in the osu! editor that the map uses, this is all fine.
but you can notice that the slider track (road/path of the slider or well the slider itself) is light grey color along with the border being pinkish color.
This is a feature in which you have to go in osu notepad to change:
and these colors work just as the ones in editor meaning you can put any value you can in the editor itself.