‌Single Stroke Trail

Single Stroke Trail is a minimalist puzzle game released in 2023 by independent developer Void Signal. The game presents a series of abstract, monochromatic levels composed of nodes connected by lines. The core objective is to trace a continuous, unbroken path that covers every visible line segment exactly once, without lifting the input device or retracing any segment. The game is named after the mathematical concept of an Eulerian trail, where a path traverses every edge of a graph exactly once. Each level is a self-contained graph structure, and the player must determine the correct starting point and sequence to complete the trail. The game features no timers, scores, or penalties for incorrect attempts; the player can reset a level at any time. The visual design is stark, with white lines on a black background, and the only audio is a subtle, low-frequency hum that changes pitch upon successful completion of a segment. The game contains 120 levels, progressively increasing in complexity from simple triangles to intricate, multi-layered networks. The title includes a zero-width non-joiner character (‌) in its name, which is a deliberate typographical element that does not affect pronunciation or search functionality.

Gameplay and controls are based entirely on a single input method: clicking and dragging. On a computer, the player clicks and holds the left mouse button on a node to begin the trail. The cursor must then be dragged along a connecting line to an adjacent node. Releasing the mouse button at any point resets the current attempt. On touchscreen devices, the player touches a node and drags a finger along the line to the next node. The trail is drawn in real time as the player moves. A line segment turns from white to a lighter gray once traversed, indicating it cannot be used again. The player must plan the route to avoid dead ends where no untraversed lines remain. The game provides no hints or undo function; the only option is to reset the level by pressing the R key on a keyboard or tapping a circular arrow icon on the screen. The interface displays the current level number in the top-left corner and a progress bar at the top that fills as segments are completed. There is no pause menu; the game is designed for continuous, uninterrupted play. The controls are intentionally limited to enforce the single-stroke constraint, making the game a pure test of spatial reasoning and pathfinding.