Gameplay differences from osu!stable

This page intends to outline all the (known) differences in gameplay between osu!(stable) and osu!(lazer). Importantly, note that this is comparing gameplay without the "classic" mod applied. Some of the differences can be reverted using that mod, and in such cases it will be mentioned.

Slider head circles now require accuracy when hitting

Until lazer, sliders have only required the accuracy of a "50" / "Meh" hit to reward a perfect score. This was done for historic reasons, but feels bad for a rhythm game. Going forward, sliders will require hit accuracy for their initial click.

Breaks backwards compatibility	Yes
Classic mod revert support	Yes
Intentionally changed	Yes
Needs further consideration	No

Slider head circle follows track snaking when not hit

When a slider reaches its start time, the "head" circle will begin to move along the slider track, moving the actual hit target with it. This compares to stable, where the hit target remains at the original location.

This kind of makes sense when you look at it, but adds complexity to computing gameplay (and potentially adds frame or sub-frame replay error at a new location).

The rationale behind this change is simple: without it, having "Snaking out sliders" enabled becomes very awkward to visualise when a player hits late. Do you leave the original circle in place and delay the outward snaking? How does it catch up to the actual location of the slider ball if so? And on the contrary, if you don't delay the snaking, do you leave the head circle detached from the slider (please no)?

Breaks backwards compatibility	Yes
Classic mod revert support	Yes
Intentionally changed	Yes
Needs further consideration	Yes

Audio rate adjustments affect hit windows in osu!mania

In stable, osu!mania reverts changes to hit windows resulting from applications of DT/HT.

Breaks backwards compatibility	Yes
Classic mod revert support	No
Intentionally changed	No
Needs further consideration	Yes

Hit window edge calculations don't match stable

Stable uses a mix of comparators for hitwindows, whereas lazer uses one.

ruleset	hitobject	comparator (stable)	comparator (lazer)
osu	circle/slider	<	<=
taiko	circle	<	<=
mania	notes	<=	<=

Breaks backwards compatibility	Yes
Classic mod revert support	No
Intentionally changed	Yes
Needs further consideration	Yes

osu!taiko gamefield aspect ratio is limited

Stable stretches the taiko playfield based on window size, making the apparent "AR" or approach speed of gameplay change in line with window size. Originally we limited this completely as it can adjust playability but switched to only limiting the maximum aspect ratio due to community pushing for having it "as it was on stable" (dicussion: https://github.com/ppy/osu/discussions/13047 / PR: https://github.com/ppy/osu/pull/21883).

Breaks backwards compatibility	No
Classic mod revert support	Yes
Intentionally changed	Yes
Needs further consideration	Maybe