In Orthogonal Slide, the target can be close to its destination and still have no way forward. The next useful move often belongs to a small block somewhere else on the board. Your job is to clear the right cells, sometimes by shifting the empty space across the board in stages.
Unlike Classic Slide, these puzzles do not ask you to put every picture tile in order. Look for the targets marked with stars and the highlighted places they need to reach. The challenge is complete when the required targets reach their assigned positions; other pieces need only be out of the way.
What a piece can actually do
Pieces slide horizontally or vertically. They keep their shape and orientation throughout the puzzle. An L-shaped piece does not rotate around a corner, and a rectangle can move sideways as well as lengthways when there is room.
Every cell newly covered by a move must be empty, and the whole piece must stay inside the board. A piece cannot jump a blocker, push another piece, or join its neighbors into a group that moves as one. Several pieces may need to move in sequence, but each move must be legal on its own.
This makes the shape of an opening more important than the total number of empty cells. Two separated single-cell gaps will not admit the leading edge of a two-cell-wide block moving down.
Read the next step, not just the destination
Start with the target's next intended move. For a 2×2 target to move down one row, both cells directly beneath its lower edge must be free. You do not need another entirely empty 2×2 square, because half of the target's new footprint overlaps its current position.
If one of those two cells is occupied, identify that blocker and work backward. Where could it move? What must move first to make that possible? Stop once you reach a legal move you can actually perform.
The following example uses the initial position of Klotski. The large starred block begins at the top, and a horizontal block below it obstructs its downward route.
Make two neighboring spaces
At the start of Klotski, the two empty cells are beside each other in the bottom row. Slide the two small blocks immediately above them down, one at a time. The two empty cells end up in the row above.
Notice what has changed. The number of empty cells is still two, but they are now where the horizontal block needs them.
Use the opening you created
The horizontal block can now slide down into those two neighboring spaces. That clears the two cells directly below the starred target, allowing the target to move down one row.
These four moves show how to create space. They do not solve Klotski or establish the shortest route. The target still has to reach the highlighted lower destination. Before advancing it again, inspect the pieces below and beside it and decide where they will go.
Give blockers somewhere to wait
“Move that block out of the way” is only half a plan. Its temporary position must fit its whole shape and leave room for the next move.
For a vertical 1×2 block moving sideways, inspect the two cells alongside it. One empty cell is insufficient. For an L-shaped piece, inspect each newly occupied cell of the translated L. Its cutout may fit around an occupied square, but it does not allow the piece to rotate or squeeze through a narrower gap.
Before parking a blocker, check whether it will cover the target's route, occupy another block's only destination, or divide a useful opening. Sometimes you must move it away from the target first, then bring it back after another piece has passed.
Know when a move has helped
Useful progress can be less obvious than a target moving toward its goal. A move may connect two gaps, free a long block to move sideways, or let a trapped piece leave a corner.
When you find yourself undoing the same moves, choose one concrete intermediate goal. For example, clear both cells below the horizontal block. Keep that goal until you achieve it or identify the piece preventing it. If you return to the same arrangement without changing your plan, you are repeating the same problem.
There is no universal row-by-row method for these layouts. Pieces have different footprints, and the goal usually constrains only part of the board. Even pieces that seem settled may need to move again to release a blocker.
Choose a practice board
Start in the Easy Puzzles collection, then try the Classic Puzzles collection. Shorter solutions are useful for reviewing an entire chain of dependencies. Klotski is better approached after you are comfortable creating and relocating openings.
If you use the solver for help, pause after one suggested move and identify which new move it enables. Then try to predict the next step yourself. A solution sequence is easier to learn from when you can explain why each temporary displacement was necessary.
Additional resources
- Jim Storer's puzzle archive documents physical sliding-block puzzles, including layouts and solution material.
- Rob's Puzzle Page on sliding blocks compares historical designs and explains the variety within this puzzle family.
- The Puzzuzu glossary explains orthogonal movement, piece footprints, and state space.
Open an Orthogonal Slide challenge and choose the target's next step before moving anything. Name the cells it needs, then work backward until you find a blocker you can move now.