What zeros the two rail wells?

The small blue block through the bottom blue gate zeros the right well; the blue vertical through that gate zeros the left well.

What are the final three blocks?

Lime L goes through the left green gate, yellow vertical through the bottom orange gate, and dark-green horizontal through the top green gate.

Block Out level guide

expert 9 colors

Super Hard Level 669 uses separate last pieces for twin 1-covers and rail wells, two purple keys for the chain neck, and an exact three-block finish.

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

Remove the first purple key carrier from the lower-left pocket so the chained neck marker drops from 2 to 1.
Send the orange vertical through the left orange gate; the orange cover changes 1 to 0 and exposes a framed red square, red pieces, colored columns and framed purple vertical.
Shift the lime L right as the first post-reveal move, then send the cyan block through the top cyan gate; the pink cover changes 1 to 0.
The pink cover exposes a blue/cyan cluster, pink L, red vertical and second purple key carrier; pull the lime L right first, then remove the second key so the chain changes 1 to 0.
Pull the released purple vertical down through the neck and keep the shared column empty.
Send the small blue block through the bottom blue gate; the right rail well reaches 0 and reveals lime L, yellow and pink verticals, cyan, green and red horizontals. Pull its red horizontal into the neck first.
Send the blue vertical through the bottom blue gate; the left rail well reaches 0 and reveals purple L, lime pieces, red/cyan verticals and pink horizontal. Lower its cyan vertical first.
Move the right-well red horizontal and pink vertical through the neck before the left-well cyan vertical, lime pieces and pink horizontal.
Finish lime L through the left green gate, yellow vertical through the bottom orange gate and dark-green horizontal through the top green gate; BLOCK OUT, fireworks and the Level 669 reward panel confirm completion.

Colors in this level:

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

Trying to pull the chained purple vertical before the second purple key changes its marker from 1 to 0.
Sending both rail-well fronts into the neck at the same time.

Small blue through the bottom blue gate zeros the right well; blue vertical through the same gate zeros the left.
Send the right-well red horizontal and pink vertical before lowering the left-well cyan vertical.

Board notes 5 details

Layout: Pink and orange 1-covers fill the upper-left, exposed cyan/yellow/lime/pink pieces sit upper-right, and a chained purple counter occupies the neck above the lower pocket.
Goal: Use both purple key carriers to release the neck, zero each cover and rail well with its own last object, then send the two well waves through the neck in order.
Opening: Remove the lower-left purple key first, send the orange vertical through the left orange gate and keep the top cyan block aligned with the top cyan gate.
Danger Zone: Feeding the left and right rail-well fronts into the neck together traps the right red horizontal and left cyan vertical.
Mechanics: Orange and pink 1-covers, two purple keys, a 2-to-1-to-0 chain, and separately triggered gold rail wells create the level's linked states.

What zeros the two rail wells?
The small blue block through the bottom blue gate zeros the right well; the blue vertical through that gate zeros the left well.
What are the final three blocks?
Lime L goes through the left green gate, yellow vertical through the bottom orange gate, and dark-green horizontal through the top green gate.