Exploit allowing Manipulation of Perceived AR in Lazer

[Ashclown]

Type

Game behaviour

Bug description

Description of the Issue

An exploit in lazer lets players manipulate perceived AR and reduce reading difficulty by adjusting skin and gamma levels.

Explanation of Variables in Play

• Hitcircle light-up: refers to the circle's brightening that occurs before a note is pressed. This varies based on mods rather than the map's base AR, namely HT will increase the duration, and DT will decrease it by a considerable margin.
• Kiai lighting: During Kiai sections, the hitcircle.png and slider body flash. This causes every visible note to exhibit the brightening effect simultaneously, regardless of the mod or AR. This makes these sections near-impossible to read.

Key Differences between Stable and Lazer

The interaction between these variables differs significantly in stable and lazer, making exploitation possible only in the latter.

In stable, hitcircle.png undergoes both the light-up and Kiai animations, making it exploitable only on maps without Kiai sections. hitcircleoverlay.png is affected by the light-up but not Kiai animations, but Kiai flashing on the slider body complicates readability (e.g., Scarlet Rose). Hitnumbers are unaffected and pose no issues.

In lazer, the hitnumbers are affected by the light-up animation but not Kiai flashing. The slider body also remains unaffected, enabling the exploit demonstrated in the video. The other elements behave a bit differently but not in a way that is relevant.

Problem at Hand

Players can exploit gamma settings with an instafade skin (e.g., fully white or opaque), creating the illusion of higher AR, even on low AR maps like AR-5, significantly lowering the difficulty of dense maps. Approach circles are removed on video for comfort.

The absence of Kiai flashing on the hit numbers allows the exploit to function flawlessly, unlike in stable.

Proposal

The following solutions are proposed:

• Remove the light-up effect from hitnumbers, aligning their behavior with stable, or add Kiai flashing to them to mitigate exploitability.
• Consider removing the light-up animation altogether. While this solution has been previously discussed, it would be the most ideal.

Regulating gamma adjustments themselves is impractical, as they can be influenced by undetectable factors.

Screenshots or videos

lazer.ez.gamma.cheese.mp4

Version

2024.1208.0

Logs

compressed-logs.zip

[peppy]

I've touched on this a couple of times in the recent past. This is a known difference.

Not sure we need to care, though. It's just another example of skins doing stupid stuff which some players classify as "exploit" and others classify as "required in the game because it's been that way for a decade". There's likely tens of similar cases you could subjectively call "exploits".

Needs further community discussion.

[koopafou]

EZWC is going on right now and the controversy is creeping back up.

Proposal : randomize the timing of the glowup or the transparency rampup (or make it differ according to white/red/blue tick ?) to break gamma abusing skins, thus making circles appear out-of-order on them.
You would need to make sure it's not obvious at gamma 1, but tbh those skins aren't obvious either until you go below 0.3, at this point it's very sensitive to brightness changes. You might even have fun by ramping the transparency with a slightly non-monotonous function to make the circles blink.

[Taneta-nemausernames]

"Consider removing the light-up animation altogether",
Surely this, the flash bangs just don't stop.
The kiai flashing and light up animation is a ploy by big optical

[real-eo]

I can't manage to reproduce the bug, can someone provide a skin by link? I understand how the bug works (i think), but i can't seem get the effect showed in the video above

[Ashclown]

Needs further community discussion.

Plasma recently highlighted this exploit in a Twitter thread, bringing the general community's awareness to the issue. Hopefully, some more consideration will be brought to this topic, as many players have showcased the extreme unfair advantage the exploit provides.

If the light-up mechanic needs to remain in the game, an alternative approach could be to tie the light-up to the AR in such a way that reduces exploitability. For example, triggering the light-up only within 50ms or less after a note appears would render it largely ineffective on maps AR5 and below.

[Mof10]

Adding another comment here to bring attention to this issue. As a low AR player / reader, it feels incredibly disheartening to know that a skillset that is already very niche can be possibly trivialized entirely because a fix 'simply doesn't seem important'.

[koopafou]

master...koopafou:osu:gamma-skin-troll
I implemented my proposal in this branch, I'm going to have EZ and "EZ" players test it out.
I will cleanup formatting later, also values might be subject to changes in case it's not strong enough or the trick is too obvious on normal skins at normal gamma. It's also unclear why the delay offset is constant now, when it seemed to vary before according to the actual hit window.

[moorf]

I suggest making the "hitcircle light-up" non-existent at lower AR.
This way, it wouldn't affect 95% of players.

[wanderingbonzi]

Honestly, this needs immediate attention and a fix. This exploit makes low ar and negative ar reading a joke. Maybe do what another user suggested, and disable the light up animation below a certain ar.

[vekt0r-github]

Just adding some context that as far as I know, the reading player community didn't consider this common knowledge, much less "required in the game because it's been that way for a decade". The twitter thread linked above allegedly has the instructions to replicate the behavior in the video on stable (I can't check, please correct me if I'm wrong). From the limited discussion I've seen on "gamma skins" players used, they were nowhere near this game-breaking for low AR.

When you're able @peppy, I think it'd help greatly to give your opinion on if investigating a fix can be prioritized, or any reasoning behind this feature/other blockers to patching it we may have missed. Even better would be evaluating @koopafou's patch linked above! To be frank, EZWC is a little bit on fire right now due to the sudden tweet publicizing this, and staff+players are looking for direction which relies on this info. Thanks!

[Ashclown]

Just adding some context that as far as I know, the reading player community didn't consider this common knowledge, much less "required in the game because it's been that way for a decade".

This is correct. A handful of players had experimented with gamma stacking on stable, but it was niche because of kiais. The Lazer instafade method had never been brought up anywhere I could find, and judging by my conversations with others testing these mechanics, was most likely still undiscovered.

[peppy]

Adjusting gamma to exploit the game is going against fair play rules. Doing so will be treated the same as other kinds of cheats. Please refrain from doing so, if/when we action against this kind of behaviour, there will be no window for "oh i didn't know that was cheating".

If this is affecting a tournament, then the entrants are likely in a very grey zone and face potential account restrictions going forward. If usage of such skins is as rampant as you say, cancelling/postponing the tournament may be in your best interest.

[Mof10]

I think the issue is that there isn't any good way for tournament hosts (short of asking for a liveplay with a camera pointed at the monitor, which is impractical for a tournament at scale) to determine whether or not someone is using this exploit.

Now that it's been publicized - and the relative ease of using the exploit is well known (relatively popular posts on Twitter and Reddit), in my opinion, the only way to certifiably say that we're all playing on fair ground in terms of low AR in general is to get a proper fix.

As you say, postponing the tournament might be the best step for the present moment, but I think that this is absolutely something that requires some sort of action given the point I made above. It's too easy, (as far as I know) undetectable, and provides far too big of an advantage to simply let slide now that the cat's out of the bag.

There's already a branch with a possible solution (see @koopafou 's comment above), so it would be nice to see further discussion about what can actually be done and whether koopa's proposed idea would work. Not sure about stable.

[peppy]

The linked branch is not a valid option. It changes a core gameplay mechanic in a breaking way which will make normal gameplay shocking.

I don't have anything further to add here. We will not be making any immediate changes, but as above, adjusting gamma beyond normal levels (±1020%, or a range of about 2.02.4 in raw gamma numbers) as per screen calibration requirements) is NOT ALLOWED for ranked gameplay. We can already detect such a change, and may start to enforce restrictions for it. I'd highly advise that you tell players not to do this, even if it's "easy".