So it turns out we don't have anything in the ranking criteria regarding overmapping. Something like https://osu.ppy.sh/s/659614 is 100% rankable in catch because nothing says it can't.
Taking from the standard rc works mostly fine
With a few modifications, we can use mania's new rc better fits to cover it.
Taking from the standard rc works mostly fine
All circles and slider heads should be snapped to distinct sounds in the music. Adding hit objects where there is no musical cue to justify them can result in unfitting rhythms.
but results in things like 1/8 buzz sliders made out of circles being unrankable (eg https://osu.ppy.sh/s/468281) which doesn't work.With a few modifications, we can use mania's new rc better fits to cover it.
All circles and slider heads should correlate to a sound present in the music. This is usually a distinct sound, but can also represent a continuous sound with an indistinguishable start or end.
You can find the original guideline I copied here. There are a few extra bullet points I removed because they only apply when you have to actively play each note, which only applies to mania.