Match pairs of free tiles to clear the stack. A tile is free if no tile sits on it and at least one side is open.
Tap a tile to select it, then tap a matching tile of the same type to remove the pair. Both tiles must be 'free' — no tile resting on top, and at least one of the left/right neighbors at the same layer must be missing.
Layers stack from the bottom up. Bottom-layer tiles need their sides cleared, upper-layer tiles need to be exposed by removing what's beneath them.
Score: +10 per pair cleared, +200 bonus for clearing every tile in the layout. The game ends when you clear the whole stack OR no matching free pair remains (deadlock).
New Game shuffles a fresh layout. Random shuffle can occasionally lead to unsolvable starts — accept the deadlock and try again, that's part of the genre.
Always look top-down. The topmost layer is most constrained — match those tiles first when you have a choice. Tiles buried under upper layers don't matter yet; spend your decisions where they unlock the most.
Before each match, scan for tiles of the SAME type still sitting on the board. If you remove two copies of type X but two more X tiles are buried in awkward positions, you've made progress; if all four X tiles are visible at once, you have flexibility — choose the pair that unlocks the most blocked tiles.
Watch for 'paired blockers'. Sometimes two free tiles of the same type are blocking each other — removing them clears the whole column. Other times, all four free tiles of one type are mutually blocking and you're stuck. Look ahead 2-3 moves before committing to early removals.
Don't waste 'free choice' tiles. When all four of one type are free, save one pair for later — they'll unlock something else once you've removed surrounding tiles. Burn them too early and you might find you needed that column open to free a different type.