Sever the shadow tethers before the sapphire core runs out of light
A faceted sapphire core burns alone at the centre of the dark. It is the only light left, and the dark has noticed.
Shadow leeches crawl in from the edges of the screen and latch glowing tethers onto the core. Every tether that holds drinks the light out of it. Your finger is the blade: swipe across a tether and it parts, the leech recoils, and the core keeps burning a little longer. Clear the level's quota of severed tethers before the light gives out, and the dark falls back.
It sounds simple until the leeches start arriving with defences. Shielded threads refuse the blade along most of their length — only the thin bright segment at the middle will part, so a lazy swipe across the whole thread accomplishes nothing but wasted seconds. Armoured leeches take the cut, drop away, and then crawl straight back for a second attempt, which means a tether you have already dealt with is not necessarily a tether you are finished with. Watching which ones return, and deciding whether to cut them again now or hold the blade for something more urgent, is where the real game lives.
That pressure builds across fifteen levels. Early on there is room to breathe, to learn the rhythm of a single swipe and see the core's glow steady itself afterwards. Later the tethers arrive layered and overlapping, shielded threads crossing armoured ones, and the question is no longer whether you can cut them but in which order. The core's light is a clock you can see, dimming in real time, and every hesitation is written into it.
Control is one gesture, used well. No buttons to learn, no menus to fight through mid-level: you look, you choose, you swipe. The difficulty is entirely in the choosing. A player with fast hands and poor judgement will lose the core just as surely as a careful player who swipes too slowly, and the levels are built to punish both habits in turn until you find the balance between them.
The art is cut glass and cold blue against black. The core sits in the middle, throwing coloured light across the facets, and the leeches read as silhouettes until their tethers catch fire with the light they are stealing. When a thread parts, the glow snaps back towards the centre. It is a small, satisfying thing, and across fifteen levels you will chase it hundreds of times.
One core. One blade. Keep the light alive.