Evening wrote:
0.01 - 0.10 SV, though is apply-able in the editor, doesn't seem to be giving their correct scrolling speed effect since if you'd add a 0.01x next to a 0.1x, it doesn't seem to change speed.
The same thing applies to 8x SV>infinity, where it forever caps out at 8x scroll rate no matter what. Negative SV values are also treated as positive when you manually edit them in notepad (SV is denoted as -number.decimals in the editor, so negative SV would be either number.decimals or --number.decimals, both result in positive for the notepad, and negative in the editor). Baraatje talked about how this cannot work in the physical sense, as in how the notepad file would outright reject this, but I'll talk about how if it were to accept such values, this is probably how osu! would react, going off of observations from how songs react to current BPM/SV changes.
In terms of negative BPM/SV, it really only works the best in mania, as others have pointed out, as how mania works is when the timing point is hit, all notes on the screen at the time are affected. So if a BPM had approached 0, all the notes in mania would stop. Theoretically, if the BPM or SV was negative, all the notes on screen would scroll backwards if going off of how the osu! engine registers notes in mania.
In Taiko, BPM/SV changes are treated entirely different, where only the notes on or after the BPM/SV change are affected. In Taiko maps, you might've noticed notes suddenly slow down or speed up, despite the notes you're hitting not doing this, and that's because the notes you can see up ahead have hit a BPM/SV change, which causes them to scroll at a different rate. So say theoretically if BPM or SV had reached 0. Going off of this knowledge, all that would happen is that the notes inside the SV change would stay stuck at the hit reticle until their time came to be hit. Firce777's map (
https://osu.ppy.sh/s/219733) displays this, where the BPM is set to 600000 in the notepad file. This corresponds to an extremely low BPM (approx. 0.01666666666BPM, or 1BPH (1 beat per hour)). Going off of this knowledge, a negative SV would likely make the notes come from the left side rather than the right side, which admittedly could make for some creative gameplay, probably would be somewhat infuriating to play.
Since there is no definite way of telling of osu! or CTB would operate, we can only speculate. As osu! and CTB are different in where they use AR values rather than going off of the BPM/SV for their notes, we can't make too many assumptions. The one thing that does use BPM/SV in osu! and CTB are sliders, in where if it were a negative BPM, it'd probably just play in reverse, which isn't too interesting all things considered. At the moment, a BPM/SV approaching 0 doesn't affect anything in osu! or CTB in terms of notes, even if the sliders are. If we were to assume in osu! or CTB that it would act similarly to Taiko however, as sliders act exactly the same as notes in Taiko in terms of when they get affected, a BPM/SV of 0 would freeze the note's animation when it was approached, but would still have the same AR/OD timing window, making it rather unfair to be perfectly honest. You would end up having notes cluttered on the screen, not moving anywhere until they're hit, and with how large the approach circle is, it could become distracting very quickly, though depending on what was done with it, could also create some interesting artistic decisions. A negative BPM/SV would have the note's animation play in reverse if we're still going off the same philosophy as before, which would mean that the AR/OD timing window still stays the same, but instead, the player might have to hit the note at around the largest the approach circle can get, and this would be very interesting, maybe even fun to play, unlike a BPM of 0. These changes would probably apply to CTB as well, and again although the negative BPM to make the fruits fly to the top with you still needing to be lined up with the fruits could be interesting and fun, a BPM of 0 would have the note frozen at the top, possibly off-screen, and you'd still have to catch it, which would again be aggravating, though unlike in osu!, this wouldn't even be artistic if you can't see the fruit. An important question might come up as "what about the spinners?". Spinners are mapper controlled in terms of how long they last, and they play no differently from a BPM/SV perspective, so they'd likely act the same.
tl;dr, this idea works really well in mania, okay in Taiko, and while negative could be fun in osu! or CTB, a BPM/SV of 0 in those modes would be infuriating and virtually unplayable without some kind of storyboard.
