Logjam

How to Play Logjam

Logjam is an axis-constrained sliding-block escape puzzle. The board holds a 6×6 grid of rectangular wooden pieces — each one can only slide along its own long axis. Horizontal logs slide left or right; vertical logs slide up or down. Your goal: slide the crimson escape log all the way to the gold EXIT gap on the right wall.

Start by clicking or tapping any piece to select it — a gold border highlights your selection. Then drag the piece in the allowed direction, or use the arrow keys to nudge it one cell at a time. To free the escape log you must reposition every blocking piece out of its row. Sometimes that requires sliding a column of vertical pieces to free a horizontal blocker, which then frees the row for the crimson log — chains of three and four moves are common at higher difficulties.

Each puzzle has a pre-computed optimal move count. Solve in that count plus two and you earn 3 stars; plus five earns 2; anything beyond earns 1. Resetting the counter is free — it does not penalise your final rating — so explore freely and retry until the path clicks.

Controls

• Click / tap a piece to select it.
• Drag the selected piece along its axis to slide it.
• Arrow keys nudge the selected piece one cell at a time.
• Reset button (top-right) restarts the current puzzle from its initial layout without penalty.
• Tier buttons (Beginner / Medium / Hard / Expert) switch the active puzzle set once unlocked.

Strategy Tips

• Work backwards from the exit row. The escape log sits in row 2. Identify every piece blocking that row and plan each displacement in reverse order before touching anything.
• Look for free slides first. A piece that can already slide without displacing others is your free move. Use it to open space for the piece that actually matters.
• Vertical blockers in the exit row are the hardest. A vertical log crossing row 2 needs to be slid entirely above or entirely below — which often requires clearing two or three cells in its column first.
• Chase 3-star efficiency on Beginner before moving up. The optimal-count discipline on easy puzzles trains the read-before-you-move habit that Expert requires.
• Daily puzzle mode posts your move count to a shared leaderboard. The same puzzle appears for every player each day — come back after your first solve to improve your position.

The History of Sliding-Block Puzzles

Sliding-block puzzles trace their origins to the 1870s, when Sam Loyd popularised the "15 Puzzle" — a 4x4 grid of numbered tiles with one blank space, where the goal was to arrange the tiles into numerical order by sliding them into the gap. The puzzle swept through North America and Europe as a popular mechanical toy, and mathematicians quickly established which starting configurations were actually solvable (exactly half of the 10 trillion possible arrangements can reach the goal state).

The axis-constrained variant — where pieces are locked to a single direction of movement — emerged as a more tractable design space for puzzle designers. Instead of one blank tile enabling all movement, each piece's shape determines what it can do: a horizontal plank can only slide along the row it occupies; a vertical post can only travel up or down. This constraint makes the puzzle harder to solve by feel and much harder to brute-force by eye, because the number of possible move sequences grows explosively with the number of pieces.

The best-known commercial version is Rush Hour, introduced by Binary Arts in 1996 and still one of the best-selling logic puzzle games worldwide. The red car — always a 1x2 horizontal piece — must reach the exit on the right side of a 6x6 grid while a field of trucks and cars sits in the way. The genius of the design is that every puzzle has exactly one solution path, yet the shortest solution can require dozens of moves that feel completely counterintuitive until the right perspective clicks. Logjam follows the same core mechanic and preserves the 6x6 board and right-side exit that define the classic format.

Computer implementations added depth the physical toy could not: infinite puzzle libraries, solution-optimality tracking, daily challenges shared across players, and leaderboards that turn a private pencil-and-paper exercise into a competitive sport. The "fewest moves" metric — Logjam's daily leaderboard currency — rewards a fundamentally different skill than speed: the ability to read the full dependency graph of a puzzle before touching a single piece, planning the minimum-cost sequence that unblocks the escape log without creating new problems downstream. It is one of the cleanest measurements of spatial reasoning the puzzle genre has devised.