Tile Arc Wonder

Tile Arc Wonder gives you a grid and a pattern hidden inside it.

Each tile in the grid holds two quarter-circle arcs. The arcs are always there — curving from the midpoint of one edge to the midpoint of an adjacent edge. Every tile has exactly two orientations: arcs in the northwest and southeast corners, or arcs in the northeast and southwest corners. Tap a tile and it flips between them. That is the only interaction.

Behind the grid, barely visible, sits the target — a ghost pattern in faint amber showing which orientation every tile should have. Some tiles are already correct, their arcs glowing gold. Others are wrong, showing in blue. The puzzle is complete when every arc in the grid matches the ghost.

What makes it extraordinary is what happens visually as you solve it. Each correct tile is a piece of a larger continuous curve. As blue tiles turn gold, isolated arc fragments connect to their neighbours. Short disconnected curves grow into longer ones. Longer ones merge into rivers. In the final moments of a well-solved puzzle, the last few blue tiles flip to gold and the entire grid suddenly reveals itself as a single flowing path — one unbroken curve that winds through every tile in the grid, touching every edge, filling every corner.

This is a Truchet tiling. Sébastien Truchet, a French monk, described these tiles in 1704 and noted that random arrangements produced unexpectedly beautiful patterns — organic, flowing, resembling rivers and knotwork and calligraphy. The patterns appear across Islamic geometric art, Celtic illumination, and modern generative design because they arise naturally whenever curved arcs are placed in a grid. The mathematics is simple. The results are endless.

The ghost pattern is always achievable. The locked tiles — marked with a faint gold border — are pre-set to their correct orientations and cannot be flipped. They are anchors. The remaining tiles are yours. A hint will fix one wrong tile, but you have only three.

As your score climbs the grids grow larger. The number of locked tiles decreases. The target patterns shift from loose arrangements to single-loop configurations — where the correct solution produces not just any set of curves but one specific unbroken path through every tile simultaneously. Finding that path requires not just pattern matching but understanding how each flip affects the connectivity of the entire grid.

No ads. No timers. No prior knowledge of geometry required. The arcs are self-explanatory. The pattern is always visible. The satisfaction of a completed grid — the moment everything turns gold — is available to anyone willing to keep tapping until the river finds its way.