Something wrong, or just stuck? Write to dev@tylersmith.art.
Every board can be solved by reasoning alone — no puzzle in Catcross ever requires a guess. The hint button explains the next logical step rather than simply giving an answer. If a board still defeats you, it can be skipped after a few hints; that opens the next level, though it scores nothing.
The Learn button in the toolbar teaches each stage in about a minute, and stays available for good — you can revisit it at any time.
Progress lives on your device, not on a server, so deleting and reinstalling the app clears it. Restoring an iPhone backup that predates your progress has the same effect. There is unfortunately no way to recover progress once it is gone.
Leaderboards need Game Center: open Settings on your iPhone, tap Game Center, and make sure you are signed in. Average-time boards only rank you once you have solved enough puzzles at that board size, so they read as unranked until then.
No. Catcross is entirely offline. Game Center leaderboards are the only feature that uses a connection, and they are optional.
dev@tylersmith.art — I read everything that comes in.