Loop deduction puzzle

Fathom

A few numbers. A few markers. One loop, hidden in plain sight.

Draw a single closed path on a dot grid. Each number tells you how many edges touch its cell. Inside and outside markers add the deeper question: what does the loop contain?

• Pure deduction No lives, streaks, timers, or guessing pressure. Invalid states are information, not failure.
• Marker logic Filled and open markers ask whether cells belong inside or outside the final loop.
• First-class notes Mark edges with X when a path is impossible, then refine the board one constraint at a time.
• Offline puzzles The launch puzzle bank ships with the app, so owned content remains playable without a connection.