Connect every pair. Fill every square. That is the whole rule. It is harder and more satisfying than it sounds.
Synapse is a logic puzzle in the numberlink family: draw a path between each pair of matching nodes so no two paths cross and every single cell is filled. Not most cells. Every cell.

FOUR WORLDS · FOUR MECHANICS · ONE APP Most games in this genre sell each twist as a separate app. Synapse puts all four in one, and every world unlocks by playing - never by paying. · Cerebrum - the classic board. 1,000 levels. · Axon Reach - a wrap around torus; leave the right edge, return on the left. The board has no edges. 500 levels. · Corpus - paired portals teleport a path across the grid. 500 levels. · Plexus - bridge cells carry two paths at once, one over, one under. 500 levels. 2,500 hand verified levels in total, each generated and then validated: a guaranteed solution filling 100% of the board and a designed difficulty curve that breathes rather than spikes.

A UNIVERSE YOU NAVIGATE Your progress lives inside a 3D solar system. Pinch to zoom from four worlds in orbit down to a single region map - one continuous move, not two screens. The orbits are modelled on real orbital mechanics: planets accelerate at their closest approach and drift at their farthest. Complete a region and it lights up; complete a world and its map resolves into a symmetric figure.

MAKE IT YOURS Earn Neurons by playing and spend them on cosmetics: the central star, the orbital trails, the background sky, the beams between regions. The Constellations sky renders 57 real constellations from a star catalogue. The Deep Field sky is modelled on James Webb Space Telescope imagery. Around 96 items and 500+ combinations - all bought with earned currency, none with a gameplay advantage attached.

BUILT TO BE FAIR · Every level is free to reach and free to play. · No energy. No lives. No timers gating play. · Reset as often as you like, for free. · Hints are optional and cost earned currency. Synapse is free to play and ad-supported, with optional in-app purchases and a subscription for players who want to move faster or skip interstitial ads. You can complete the entire game without spending anything.

CRAFTED TO PLAY AND HEAR Twelve luminous path colors on a near black board. Every connection plays a note whose pitch tracks how much of the level is done, so each puzzle resolves like a finished phrase. Graduated haptics. A completion sequence that ignites outward from your own final connection.

Plays fully offline. No account, no login, no network required.

Connect every pair. Fill every square. Then rebuild the universe around it.