THE UPCOMING PP REWORK: A Comprehensive Half-Layman, Half-Technical Rundown

Good evening osu! gamers.

As you may know, for the past 3-ish months, I have been posting updates about the upcoming pp rework. Many of these times I have provided some short explanations about each change, major or otherwise.

In this post, I will attempt to detail all of the major AND minor changes, in a half-layman, half-technical way, as the title suggests. All this for the benefit of the average osu! gamer's understanding of what's happening, before the official news post drops with the deploy.

I will go through the major changes in a lot of detail first, and then explain the minor ones through short one-liners near the end. Keep in mind, the general value trends of each change might not materialize exactly as you expect, since most maps are being hit by more than one change in more than one direction.

Strap in! This is probably the biggest single rework drop since ppv2's inception so there's a LOT to cover.

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1. KWOTAQ READING

Currently, the live Aim and Speed skills have both a high AR and low AR bonus, above 10.33 and below 8, respectively. Crucially, these bonuses do not account for the density of a map at all, which causes a few major issues.

First, they massively inflate the value of high-end, high-BPM maps where high AR is actually easier to read than lower AR. For example, a 400BPM jump map will nearly always be much more difficult to read at AR8 than at AR11, but it receives absolutely no bonus for the former and receives a massive bonus for the latter.

Second, they're very limited at rewarding low AR reading. A flat multiplicative bonus to Aim and Speed for specific AR values just isn't very easy to balance in a way that rewards difficult low AR reading while also not being completely broken in the right edge cases (looking at you, A-TYPE).

Lastly, since they're flat multipliers to the Aim and Speed values of a score based on the AR value, they don't properly reward high AR reading in many cases where it is actually very difficult. For example, low-difficulty maps provide very little base Aim and Speed for an AR multiplier to scale off of, despite something like AR11 still being objectively difficult to read, in the average case.

To address these issues, a new Reading skill has been developed by kwotaq to entirely replace these bonuses (along with HD's bonuses).

The current implementation is pretty basic, yet effective, and much better than live pp (which is the important part). It's mostly based on density with a few other considerations, like velocity and angle repetition. HD has its own slightly more complex difficulty calculation inside Reading as well.

The general trends you should expect to see from this change:

-A lot of the high-end, high-BPM range of DT plays (whether it be aim or flow aim) will see significant deflation, as they have been historically inflated due to how inappropriately strong the high AR bonus is at this density.

-Reading very high AR on lower difficulty maps will now actually be rewarded, even if the maps' mechanical requirements are not as high, as Reading is its own value rather than a multiplier to Aim or Speed.

-Low AR reading will generally be compensated a lot better now, especially in combination with HD!

This change does NOT yet have any considerations for the difficulty of reading complex rhythm, or things like the overlappiness of a map. Think of it more in its current state as just Aim reading, and as doing a much better job than the live bonuses do.

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2. BASIC AIM SEPARATION

Not a lot to talk about for this change in terms of value trends, as while it's massively important for pp development as a whole, it does not yet change values drastically from live. Here's a brief rundown regardless.

Since ppv2's inception, pp has had a structural issue where Flow Aim is actually just not real at all. All of aim is packaged into the singular Aim evaluator, while Flow Aim only semi-exists as a bonus in the Speed evaluator when tapping difficulty is combined with spacing (distance bonus).

This causes some serious issues, aside from the obvious conceptual problem of there being any kind of aim difficulty at all inside the Speed evaluator.

For starters, this means that circles with any amount of spacing actually double-dip in terms of aim difficulty. They already get it from Aim, and then also get it from distance bonus in Speed, within the exact same pattern.

It also means that the Aim evaluator is strictly limited in what it can do, as certain concepts of difficulty do not translate to both Snap Aim and Flow Aim. For example, wide angles in Snap Aim are hard, but mean very little in terms of Flow Aim. Because of this, you have to add checks such as a harsh repetition penalty for wide angles to make sure Flow Aim doesn't explode, despite repeating wide angles being no less difficult than non-repeating wide angles in Snap Aim.

Essentially, the lack of aim being separated into Snap and Flow has caused insane headaches in pp development and in the viability of making meaningful improvements to the system. Having this separation, even in its basic state, is a huge improvement to the general workability of pp, and opens the doors for a multitude of changes that would otherwise be impossible.

As of right now, the only bundled value change that you should expect is a basic nerf to circular flow spam streams, with everything else related to Flow having similar values to live pp.

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3. PARTIAL D/T^2 FIX (STRAIN INFLUENCE REDUCTION)

Currently, due to how strain works, base Aim difficulty is calculated as approximately distance/time^2 (or d/t^2). This is despite pp research concluding that basic Aim difficulty in reality actually scales as just distance/time (or d/t).

Aim being d/t^2 in live causes some significant issues, especially the higher up in skill level you go.

The first issue is that high distance aim at lower BPMs is noticeably underweighted. You'll notice this the most with extreme examples such as GranDSenpai's Loved Kigurumi Sungeki, but it generally applies to a lot of regular NM aim as well, and somewhat to precision maps (although they are partially compensated through a specific small circle bonus).

The second issue is just the opposite, being that lower distance aim at high BPMs is noticeably overweighted (specifically its Aim value). It is one of the reasons that high BPM aimslop was so dominant at the high-end of pp, and still is to this day for high-end Aim in general.

Due to several systematic pp improvements, both value-wise and code-wise, it has been made possible to slowly nudge Aim evaluation towards the ideal d/t scaling. For now, Snap Aim is evaluated as d/t^1.65, while Flow Aim is evaluated as (d/t)^1.45.

The reason it's being nudged this way instead of immediately moving to d/t is that the extra difficulty of snapping high BPM isn't properly evaluated yet, and it will likely be nudged further towards pure d/t as the system improves.

The value changes for this should be roughly as you'd expect. In general, high distance and/or slower jumps and streams are buffed, while low distance and/or faster ones are nerfed. This does also mean that, in general, the overwhelming DT advantage over NM (and especially over HR) should be reduced.

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4. HARMONIC SPEED SUMMATION

In live pp, the way that both the Aim and Speed skills have their strains summed (geometric summation) leads to an issue where only the hardest 20 seconds or so of a map actually matter for its total difficulty. The way that longer maps are compensated is through an object-count-based multiplier to the pp value, whether those extra objects (past the hardest 20 seconds of the map) are actually hard or not.

This leads to some issues that you've probably even experienced yourself at some point.

The most obvious one is that consistently difficult long maps tend to feel underweighted, since the live difficulty-agnostic length bonus does not adequately reward them.

The other issue is that long maps with lots of filler and only one or two diffspikey sections tend to feel overweighted, as we've seen with a lot of recent pp-record-tier scores, really.

This change fixes these issues for the Speed skill, through using harmonic summation instead. Now, length bonus is no longer necessary for Speed, as harmonic summation sort of has a "length bonus" built into how it works, since it is a diverging series rather than a converging one. Along with that, peak strain reduction (a semi-arbitrary reduction of the highest difficulty sections of the map intended to combat diffspike abuse) has also been removed in Speed.

Aim pp still uses the same geometric sum as in live, so its length bonus issues remain, for now.

The general trends you should expect to see from this change:

-Long and consistently difficult maps (tapping-wise) should see a buff.

-Maps with only a small amount of spikey tapping difficulty should see a nerf. Unless...

-...the map's speed difficulty consists of only one VERY LARGE speed spike, in which case it should see a buff, as its spike is no longer reduced by peak strain reduction. The biggest known example of this would be 10 Things I Hate About Ai no Sukima [Mommy's Radiance] +DT, which gets a considerable buff.

Something to note: this also means that most maps with any meaningful amount of tapping difficulty will have their star rating rise, because while the live length bonus is entirely absent from star rating, harmonic summation builds it directly into the difficulty value. This doesn't mean that all star rating increases necessarily correspond to a pp increase! It just means that the correlation between star rating and pp values is improved, as has been the goal.

A known negative side-effect of these changes is that bursty/triple-spammy maps tend to get unfairly nerfed a bit. This is most noticeable on hybrid-ish maps like Prima Stella [Caged] +DT. This will likely get touched on at some point in the future, but for now it is just something that we have to live with, as it is a consequence of pp being improved iteratively as a complex system rather than all at once.

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5. KWOTAQ VECTORS (ANGLE REPETITION PENALTY)

One of the simplest yet most effective changes in this deploy, also developed by kwotaq.

This change adds a relatively strong nerf for repeated sharp-angled jumps, especially so for ones that repeat the same vector positions (tl;dr: patterns that stay in the same spot/patterns that don't rotate).

The general trends you should expect to see from this change:

-Modern pink hair girl farm map style N/V/X jumps get huge nerfs.

-More "normal" or old aim farm tends to stay relatively neutral or slightly nerfed.

-Uncomfortable or non-repetitive aim in general gets a noticeable buff.

Be aware that this change is axis-agnostic, meaning it hits repeated horizontals just as hard as repeated verticals (Brazil dies a lot)!

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6. STAT TAP (DEVIATION-BASED SPEED ACCURACY SCALING)

I will be oversimplifying quite a bit here since there are some overly technical aspects I'd have to get into otherwise.

In live, the Speed value of a score is essentially scaled by your accuracy percentage, with consideration for how many relevant high-difficulty Speed notes are in the map, which is then raised to the power of an arbitrary OD curve. The intention of this scaling is relatively intuitive: it tries to punish low accuracy if there are few Speed notes in a map, and tries to be less harsh the higher the OD is.

An issue remains with the arbitrary part of this scaling: it is possible to run the exact same replay with the same tapping on a map, and either gain Speed pp by lowering the OD, or lose it by increasing the OD. Obviously, this shouldn't happen, as the same level of tapping should be rewarded the same amount, no matter the OD. To do otherwise creates an "optimal" OD to pick for every map (usually on the lower end), and unfairly nerfs high levels of tapping if the OD is high enough.

This change normalizes accuracy to an "effective accuracy", statistically modeling it through tapping deviation, which takes into account the OD and amount of difficult Speed notes in a map.

In effect, this reduces the severity of the aforementioned scenario where running a replay on different ODs gets you different Speed values. There remains a point at the extreme low end of OD values where the map becomes theoretically doubletappable and thus gets nerfed, but most scores will cap out at an SS before these nerfs become a thing.

You should generally expect "low accuracy" speed scores on higher ODs to be buffed, as well as "high accuracy" speed scores on lower ODs to be nerfed.

As a note, this is not the same as "Stat Acc"! It does take the basic idea of it and applies it to the accuracy scaling of Speed pp, but the issues with the actual Accuracy pp portion of the system still remain.

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7. CHUNKING FIX (VARIABLE-LENGTH STRAINS)

If you've been around for a while, you may have heard of a little fact about how changing a map's offset can change its star rating and pp amount. That's because of chunking.

I'll be as brief as I can here. Essentially, difficulty is calculated in 400ms real-time "chunks" of a map, starting at 0ms in the audio file. These "chunks" are formally called "strains" in pp. These strains are then ordered by difficulty and summed together to reach a final difficulty value (in live, a geometric sum is used, as previously stated).

The problem is that all strains being equal length and starting at 0ms creates optimal BPMs that maximally align with these strains, as well as optimal offsets for every individual map, for either NM or DT. This introduces a form of pseudo-RNG in terms of values to every map in the game. It also has the slightly funnier effect of occasionally making it so speeding up a map can actually reduce its difficulty, and vice-versa.

This usually isn't that much of an issue... unless someone happens to map a song that has one of these optimal BPMs... and specifically chooses an offset for their map/audio that maximizes this RNG value.

In case you're unaware, this is actually what happened with Time to Say Goodbye (TV Size), as Plasma (who GD'd on the set) was aware of chunking and how to optimize it, and instructed the mapper on how to do so. This chunking effect caused all DT values on the set to be around 50-100pp more overweighted (depending on the diff) than they already were. The map being short, spikey, and of an optimal BPM causes a very large variance in potential RNG value changes with chunking, which is why it's affected so much.

Variable-length strains is a dedicated fix developed by Finadoggie to resolve all of these issues. In layman's terms, strains are now allowed to be of a variable length, as the name of the fix implies, and they are tied to the objects in the map.

This ensures that changing a map's offset cannot change its difficulty, increasing/decreasing its speed will always have the intended difficulty effect, and there are no longer any "optimal" BPMs for chunking.

The value changes for this fix are pretty much entirely RNG, as that is the nature of removing something that is creating RNG values in the first place. There will be no pattern to them, other than certain maps like the aforementioned TTSG losing pp due to having been maximally optimized, or maps like Chug Jug +DT gaining pp because they were very unlucky with their chunking.

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And that's it for what I would consider truly "major" changes!

Now, it's time for all the minor ones (that are worth mentioning)!

Ahem...

1. IMPROVED FC THRESHOLD FORMULA: Previously, a lot of scores with sliderbreaks near the end of the map were being incorrectly assumed to be FCs, even in impossible scenarios. This change addresses on the problem and reduces the amount of incorrect FC assumptions.

2. SLIDER ANGLE CALCULATION FIX: Basically there are a stupid amount of bugs and oversights with how sliders are calculated; this change fixes an issue where angles between sliders were being incorrectly calculated as very wide when this was not the case. Some unfortunate nerfs are applied to a lot of otherwise difficult slider maps, but this change is needed until more proper slider considerations are in pp.

3. SCALE STRAIN BONUS BY DISTANCE: Simple hotfix for low OD doubletappable patterns giving busted amounts of aim pp; think Walk This Way! [Expert] +EZDT or Crystalia [SB's Extreme] +EZDT.

4. ADD A BUNCH OF RHYTHM IMPROVEMENTS: Just as the name suggests, it's a bunch of improvements to the Rhythm evaluator (it's still not amazing).

5. ONLY NERF TOTAL COGNITION SUM WHEN READING > FLASHLIGHT: Essentially just a way to make sure that high Reading difficulty maps don't completely explode when you add on flashlight, as there is an assumed level of memorization already for scores with very high Reading.

6. CHANGE ACCURACY PP TO BE UNCAPPED: As the name suggests, accuracy pp is no longer capped, which also allows transferring some of its length bonus to Aim instead, which is at least somewhat difficulty-aware.

7. MAKE MISS PENALTY SLIGHTLY HARSHER ON FIRST MISSES: Simple miss penalty formula change. In effect, 1-3 miss scores are nerfed, 4-9 are about the same, and 9+ are very slightly buffed.

8. INCREASE AIM STRAIN DECAY BASE: Technical pp jargon which basically just means longer jump sections are buffed a bit, while shorter jump sections are nerfed.

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And that's all the changes for this pp deploy! (It's actually not; this is still quite a condensed list of all that actually changed, but it has pretty much everything that people should know)

I hope that not too many of you immediately skipped to the ending of this post to see if there's a tl;dr section! Unfortunately, this rework is so massive and all-encompassing that all I can give you is this:

TL;DR: 2026 IS THE YEAR OF PP!

See you at the deploy!