Fathom: A Quiet Puzzle

A single loop, hidden inside the rules. Fathom is a calm, premium logic puzzle. Draw one closed loop across a grid of dots so that every number is satisfied — and every marker ends up exactly inside or outside the loop. No guessing, ever. Just you, a few numbers, and one loop waiting to be found. It sits in the Slitherlink family, but Fathom's marker twist makes it something new: you reason not only about the numbers next to each cell, but about the whole shape of the loop — what it encloses, and what it leaves out. HOW IT PLAYS • Draw a single continuous loop on a dot grid. • Each number tells you how many of its edges the loop must use. • Inside (●) and outside (○) markers must end up exactly where they say. • Mark edges out with an X as you rule them away — deduction made visible. • Stuck? A gentle hint shows the next logical step, never the answer. PURE DEDUCTION Every puzzle is solvable by logic alone and machine-verified to have one unique solution. There's no luck and no guessing — and no fail state. Explore freely; nothing punishes a wrong turn. CALM BY DESIGN No ads. No subscriptions. No timers forced on you. No streaks, no daily-login nags, no notifications. Fathom looks and feels like a quiet newspaper puzzle page — warm paper, clean ink, and nothing competing with the board. A space to think. BUILT FOR EVERY LEVEL Three difficulty tiers — Beginner, Medium, and Difficult — plus a guided tutorial that teaches the loop, the X-mark, and the marker mechanic step by step. Effectively endless, procedurally generated puzzles mean you never reach the end. ONE PRICE, YOURS FOREVER Start free, then unlock the full game with a single purchase. No subscriptions, ever. Fathom — a quiet puzzle for people who like to think.