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Lizely

Domino Chain Reaction

Place a limited set of dominoes, push the start tile, and watch a real ordered chain propagate toward the goal.

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How to use

  1. 1.Inspect START, the goal bell, the identical open slots, and the tile budget. Tap or click open slots to place or remove upright dominoes.
  2. 2.Trace a route using shared edges only. Diagonal neighbors do not propagate. Press Push the start to run the ordered chain and display every reached tile.
  3. 3.Reach the goal to earn 200 points and unlock the next workbench. Complete all five for exactly 1,000; two distinct stopped layouts end the run.

About Domino Chain Reaction

Domino Chain Reaction is a five-level placement puzzle about planning a continuous cascade before you commit to the push. Every workbench is a fixed five-by-five grid with one START tile, one goal bell, a set of open placement slots, and a strict tile budget. Toggle upright dominoes into the open slots, study their orthogonal connections, and press Push the start. The game then performs an actual ordered propagation through the connected placed tiles. If the falling sequence reaches the goal, the level awards 200 points. Solve all five boards for an exact score of 1,000.

The rules are deliberately visible and deterministic. A falling tile can trigger only a tile directly above, right, below, or left of it. Diagonal contact never carries the reaction, and an empty gap stops that branch. The start and goal are fixed; neither consumes the placement budget. Open slots are visually identical before a push, so the board does not mark a correct route or expose a solution through labels, hidden fields, accessibility text, or data attributes. You must infer the useful chain from position, adjacency, and the number of pieces available.

Push is a real test rather than a decorative success button. The engine runs a breadth-first traversal from START using a stable neighbor order. Each reached tile is recorded, rotated into a fallen state, and numbered on the board. The Fall recorder repeats the observed sequence as compact position labels. A successful test stops when the goal is reached. A failed test stops when no newly connected upright tile remains. This makes a gap or stray branch observable: you can see exactly how far the cascade traveled without being shown the future route.

Each level permits two distinct failed layouts. Repeating the identical placement signature is deduplicated, so an accidental double press does not consume a second miss. Change at least one tile before testing again. A second genuinely different layout that still stops short closes the run. If a corrected layout succeeds after one failure, the failure history is cleared before the next workbench. Restart always performs an exact reset to level one with zero score, no placed tiles, no fallen sequence, no recorded layouts, and no terminal state.

A useful solving method begins at both ends. First inspect which open slots can touch START. Then inspect which slots can touch the goal. Work inward and count how many placements are needed to bridge the remaining Manhattan gaps. Corners are important because a single orthogonal turn can redirect the chain without requiring a special tile type. Do not spend the full budget merely because pieces remain; each placed domino should belong to a connected route or a deliberate branch you understand. Before pushing, trace the proposed sequence cell by cell and check every transition for shared edges rather than corners.

The five boards introduce the idea in stages. The first is a short direct handoff. Later workbenches require downward travel, shelf-like turns, switchbacks, and a longer final cascade. The board dimensions remain constant, so difficulty comes from spatial reasoning rather than shrinking controls or changing rules. Tile targets remain at least 44 pixels high and the complete board fits comfortably within a 390-pixel mobile viewport. On touchscreens and with a mouse, tap any open slot to place or remove a domino.

Keyboard play is scoped to the board. Focus a grid cell, move the visible cursor with the arrow keys, press Space to toggle an available slot, and press Enter to push. When focus is on Restart, Push, or Next workbench, native button behavior remains intact rather than being intercepted by game shortcuts. Closed spaces, fixed endpoints, out-of-range cells, budget overflow, solved levels, and terminal runs are atomic no-ops; they never partially alter score, placement state, or the observed sequence.

All puzzle boards and propagation rules in this edition are original product fixtures. They are not copied from an external level set and do not claim to simulate the timing, momentum, spacing, or friction of physical dominoes. The local engine models an abstract grid reaction with explicit orthogonal adjacency. Independent tests contain private literal solutions rather than production solution flags. Those tests prove every intended layout reaches the goal in the expected order, every one-tile near miss stops, budgets are exact, selected tiles are unique, failed signatures deduplicate, and the fifth success freezes the 1,000-point result.

The game runs entirely in your browser. Placement choices, pushes, fall sequences, scores, and mistakes are not uploaded for processing. No account, subscription, server request, or new download is required. Use it as a compact route-planning break, an introduction to graph traversal, or a visual reasoning exercise where the consequence of every placement becomes visible only when the chain begins.

Methodology & sources

The game uses five original 5-by-5 slot boards and a deterministic breadth-first traversal with neighbor order up, right, down, left. Start and goal are fixed traversal nodes; only legal user placements connect them, and propagation stops on reaching the goal or exhausting the connected component. Independent literal tests keep intended solutions outside production fixtures and verify exact budgets, unique tiles, ordered fall sequences, one-tile near-miss stops, 200-point levels, exact 1,000 completion, identical-layout deduplication, second-distinct-failure deadlock, failure clearing after success, restart equality, scoped cursor boundaries, and atomic invalid operations.

Frequently asked questions

How does the domino propagation work?
The engine starts at the fixed START tile and visits connected placed tiles through orthogonal edges in deterministic breadth-first order. It stops as soon as the goal is reached or no connected tile remains.
Why did a diagonal domino not fall?
Corners do not count as connections in this abstract grid puzzle. Every handoff needs a shared top, right, bottom, or left edge. The numbered post-push sequence shows the last tile the reaction actually reached.
Does the page reveal the solution before I push?
No. Open slots share the same styling and accessible description. Correct-route markers and future fall order are absent from visible text, labels, hidden fields, and data attributes; only your placements are shown before testing.

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