Number Trail is a no-framework, no-bundler browser puzzle built on Hamiltonian path theory, with Warnsdorff’s heuristic powering random puzzle generation.
Key Takeaways
Plain HTML/CSS/single JS module, no build step; puzzle files are plain text with three sections: metadata, grid, and walls – diffable in version control.
The core constraint is NP-complete (Hamiltonian path), made tractable by numbered waypoints that fix the sequence and dramatically shrink the search space.
Walls are placed only on edges outside the known solution path, so solvability is guaranteed by construction, not runtime decision.
Warnsdorff’s rule (visit the neighbor with fewest onward moves) generates valid paths on 5x5 to 10x10 grids, with snake-traversal fallback when it dead-ends.
Path rendering uses CSS grid gap as implicit grid lines and four directional arm elements per cell with data-attribute toggles – no layout reflow on state changes.
