What are the orange-brown question-mark cubes?

They are covered parts of the stepped tower. They become removable only as the active target route exposes them; they are not a shortcut color.

Is the broom booster required?

The verified video shows it in the HUD but does not establish a requirement. Preserve buffer capacity and follow the target row first.

Cube Tap Sort level guide

hard 11 colors

Open Level 15's stepped orange-brown tower in target order and protect buffer space through the final orange, peach, and purple groups.

If the player asks you to sign in, open the video on YouTube instead.

From the exposed lower steps, clear the red/magenta 2 and blue 1 groups in the opening target row.
After the tower shifts automatically, follow the refreshed cyan and green groups rather than tapping the orange-brown cover.
As the lower steps separate, take cyan/green from the middle stair faces; do not tap the orange-brown cover at the top of the tower.
When pink/peach and purple pieces occupy buffer slots, protect the last free cell for the orange end phase; the stepped board does not flush the buffer when it settles.
From the separated lower steps, take orange/peach before the final purple group, then wait for the checkmark and WELL DONE reward.

Colors in this level:

Red, Blue, Orange, Peach, Pink, Purple, Cyan, Green, Yellow, Lime, Gray

Start on the exposed red/magenta 2 and blue 1 faces of the lower steps.
Let the stepped tower settle automatically before choosing the next cyan/green face.
Once pink/peach and purple occupy buffer slots, keep a spare cell for the orange end phase.

Board notes 5 details

Layout: The opening board is a stepped tower of orange-brown covered cubes with exposed colored lower steps. Red/magenta 2 and blue 1 are active, and the buffer row is empty.
Goal: Advance from red/magenta and blue through cyan, green, pink, purple, orange/peach, and the final purple remnant.
Opening: Clear only the exposed red/magenta and blue faces named by the opening target boxes.
Danger Zone: Pink/peach and later purple cubes visibly occupy buffer slots while orange-brown cover cubes hide the next steps.
Mechanics: The stepped tower collapses automatically into separated colored cubes as target groups clear; the source shows re-presentation rather than a manual swipe. The order of the buffer-held pink/peach and purple pieces controls the late route.

What are the orange-brown question-mark cubes?
They are covered parts of the stepped tower. They become removable only as the active target route exposes them; they are not a shortcut color.
Is the broom booster required?
The verified video shows it in the HUD but does not establish a requirement. Preserve buffer capacity and follow the target row first.