Add One Stroke: Line Puzzle Game — graph theory (Euler paths) + puzzle mechanics #76

Suggested addition: One Stroke

• Website (fan site): https://one-stroke.savetimefor.fun
• Game: One Stroke: Line Puzzle Game by CyberGame Limited
• Topic: Graph theory — Euler paths, odd/even vertex rule, Seven Bridges of Königsberg
• Gameplay: One-stroke path drawing + tile flipping + row clearing (Tetris-like line clear)
• Platform: iOS (free, no forced ads, offline, ~14.5 MB)
• Scientific concept: The game is directly based on Eulerian path theory. Players must find a single continuous path that visits every edge exactly once — the core concept Euler formalized in 1736.

Why it fits this list

The game captures a real mathematical phenomenon (Euler paths / Hamiltonian-adjacent graph traversal) while being genuinely fun to play. Players naturally learn:

• Whether a graph has an Euler path (odd-degree vertex counting)
• Starting vertex selection strategy
• Graph coloring / parity concepts

Fan-made educational companion site

An independent fan site at https://one-stroke.savetimefor.fun/learn/ provides educational resources including:

• Euler Path explained — interactive guide
• Odd-Even Vertex Rule — the mathematical proof
• Seven Bridges of Königsberg — historical context
• 61 shape analyses — each with vertex count, edge count, odd-degree vertices, and Euler path feasibility proof

Suggested entry format

#### One Stroke
* [one-stroke.savetimefor.fun](https://one-stroke.savetimefor.fun) (fan site)
* graph theory — Euler paths, odd/even vertex rule
* puzzle (path-drawing + tile-flipping)
* iOS (free)