Block Out: Level 876 Color Sort Solution

To beat Level 876 in Block Out, empty a single tube as quickly as possible to establish a working buffer, merge matching surface colors, and avoid stacking full color groups over buried pieces you still need.

Opening Moves and Creating an Empty Tube

Before shifting any blocks on Level 876, inspect the top exposed layer across all tubes to find matching colors that can combine without using open floor space. If two tubes share an identical top color, transfer them immediately into an existing partial stack.

If no immediate merges exist on the top row, target the tube that requires the fewest transfers to clear completely:

Identify the tube holding the fewest non-matching pieces.
Shift those top segments into other tubes that already display matching colors.
Keep the newly emptied tube open as your primary transfer buffer rather than filling it with an arbitrary color.

Managing the Buffer Tube

An empty tube is required to cycle blocked layers. Treating an empty tube as permanent storage eliminates maneuvering space and leads to early board locks.

Follow these operational rules when managing your empty tube:

Temporary staging only: Move an obstructing segment into the empty buffer only if doing so immediately exposes a block that can transfer onto an established stack.
Immediate evacuation: Clear the parked block out of the buffer tube within two moves by relocating it onto a newly matched stack.
Dual-buffer preservation: If you manage to empty a second tube, keep one completely vacant while using the other for short-term color staging.

Mid-Puzzle Consolidation Priorities

Stacks in Level 876 reach up to four units deep. Prioritize moves that consolidate scattered colors and remove completed four-block sets from the active board.

Priority	Board Condition	Recommended Action
High	Matching top blocks can complete a full 4-block tube	Finish the stack immediately to lock the color and remove it from play
Medium	Moving a top block exposes a duplicate of a deep stack	Transfer the blocker to free the lower tier
Low	Shifting a block swaps positions without revealing new colors	Hold the move until higher-priority consolidations are finished

Prioritize consolidating colors that are split into single units across three or four separate tubes. Grouping these fragments frees column capacity across the board.

Preventing Deadlocks and Finishing the Board

Deadlocks occur when you build deep partial stacks on top of uncollected foundation colors. Before placing multiple matching blocks over an off-color base piece, run through three checks:

Confirm whether remaining pieces of that buried base color are already accessible elsewhere.
Verify that you have an open slot or partial stack available to temporarily hold the top blocks if you must uncover the base piece later.
Avoid building three-block matching stacks on top of a single, isolated bottom color unless the rest of that color is already exposed.

If legal moves drop to two repetitive options, reverse the last two transfers and route the intermediate piece into an alternate tube. Once two or three colors are permanently locked, use your remaining flexible column to siphon off single blockers and drop the fourth piece into each remaining three-block tube to finish the level.