Knots for Sailors

Each level hands you a length of rope and a sketch of a knot from an old sailing manual. Drag the rope over, under and through, and the game checks whether your knot would actually hold. Later chapters ask you to untangle a mess left by a careless deckhand, which is a surprisingly hard topology puzzle.

The look is navy and rope-beige, with a soft creak and lap of water in the background. It has 120 levels and takes around 6 hours. It is lovely for short sessions on the sofa, and anyone who sails will enjoy learning the real names. The caveat: it is phone-only, and on small screens the rope sometimes snaps to the wrong strand.