FathomOne loop. Pure logic.
Draw a single closed loop across a grid of dots. The numbers count how many edges of the loop touch each cell; the markers say which cells must lie inside the loop and which must stay out. Satisfy every clue and the loop solves itself. No guessing — only deduction.
A quiet space for thinking — logic over luck, every time.
Three rules. Endless depth.
Fathom belongs to the Slitherlink family — but a single twist turns it into something more global to reason about.
The numbers
A clue counts exactly how many of its four edges the loop runs along — no more, no fewer.
The loop
One single closed loop, never crossing or branching. It either closes cleanly or it doesn't.
The markers
A filled cell must sit inside the loop; a hollow one must stay outside. The twist that makes you see the whole board.
Calm by design.
Pure deduction
Every puzzle is solvable by logic alone — there is always a next move you can prove. Never a guess, never a dead end.
The marker twist
Beyond the numbers, some cells are flagged as inside or outside the loop. A second layer of reasoning that rewards looking at the whole board.
Unlimited hints
Stuck is optional. Reveal the next logical step whenever you like — and earn a clean-solve badge when you finish without one.
Plays offline
Hundreds of hand-checked puzzles bundled in. No account, no connection, no waiting — just the grid and you.
No ads. One price.
A quiet space for thinking, the way a newspaper puzzle section feels. No ads, no streaks, no subscription — a single unlock and it's yours.
Free to learn. One unlock for the rest.
A tutorial and a free demo teach the loop, the numbers, and the marker twist at a gentle pace. When you're ready, a single one-time unlock opens the full library of hand-checked puzzles across beginner, medium, and difficult tiers. No ads, no subscription, no consumables.
Out now on iPhone and Android.
One loop, the quiet satisfaction of a clean solve. Free to learn, with a single unlock for the full library.
© 2026 Fabulisti. One loop. Pure logic.