The rules

• You start with three small clumps of matter scattered through the galaxy, mixed in with the computer's. Nobody starts on a star: use your first pulse to send each clump to a star.
• Matter only ever goes to stars. Every send is from a star (or a starting clump) to another star. If two sends cross on the way, they fight, and whatever survives carries on to its star. Nothing is ever left floating in space.
• Rings. Each star has 1, 2 or 3 rings, depending on its size. Matter on a star fills its rings one by one; a full ring glows. Each ring fills more slowly than the one below it (half as fast again for every ring up), so a big star is a cannon that takes time to charge: firing everything means a long wait to reload. When all its rings are full, a star stops growing.
• Overflow. If more matter arrives than a star can hold, the extra spills along its intact threads to your neighbouring stars that have room. Whatever still doesn't fit is lost. When you plan a send to one of your own stars or an empty one, the ring dots on its path show it: solid dots arrive, outlined dots spill on, faint hollow dots are lost. Sending more into a fight is insurance, but anything left over after winning follows the same rule.
• Matter grows only on stars. Bigger stars grow it faster, and a star stops growing when its rings are full. Matter anywhere else doesn't grow.
• Constellations. Neighbouring stars you hold link up with threads of light. Every star in a linked group grows faster: +6% for each extra star, up to 2.5×.
• Flow. Once one of your stars is full, its extra growth seeps along your intact threads to neighbouring stars of yours that have room, so a full star keeps feeding the constellation instead of wasting its growth. A star that isn't full keeps all its own matter, so new stars can grow their first ring. Nothing flows into a venting star. Cutting a thread stops the flow along it.
• Cutting. Enemy matter flying over the middle part of a thread on its way to a star cuts it. Fighting at a star doesn't cut the threads around it. Cutting costs matter: the thread burns 2 matter plus 0.2 for every star in its constellation, so threads in big constellations are tougher. A group too small to pay is destroyed and the thread survives. A cut thread stays cut until its owner sends their own matter along it to repair it (not possible while enemy matter is sitting on it).
• Win by threads. Your score is the number of intact threads you hold, across all your constellations. Broken threads don't count until repaired, and lone stars score nothing. Reach the target (40% of all the possible threads in the galaxy), then keep it for 3 more pulses while your opponent tries to cut or take them. The bar at the top right is a tug of war: reach the white centre line. Wiping out the opponent still wins too.
• Fights are organic battles. Bigger usually wins, and the bigger side loses less. When forces are close, the fight sways and either side can win.
• Shape matters. Attack one mass from two sides at once and it takes 30% more damage. Matter sitting on a star defends 15% better.
• Scratched: you lose if your matter is wiped out, or if you hold no stars and have under a tenth of the matter left.

Controls

• Hold, then tap. Matter leaves a star in whole rings. Press and hold on your star: each full ring charges up, then locks in with a chime (1, then 2, then 3). Stop when you have the rings you want and let go: the selection stays lit. Then tap a star to send it there, and its path appears (matter can only be sent to stars). Tap a star that already has an order to undo that order; tap a selected star again to cancel the selection. (Dragging straight to a target still works too.) A star with no full ring can't send. Your starting clumps always move as a whole: hold one until it locks in, then tap a star to send it there.
• Three orders per pulse. Each side, you and the computer, can give up to three orders per pulse, and can split one mass across several of them. You can't do everything, so choose what matters most.
• On a phone: pinch to zoom, drag empty space to move around, and double-tap empty space (or the ⤢ button) to see the whole board again. Settings are under the ☰ button.
• Random events can be switched on or off before a game, or at any time with the Events button. They never come from nowhere: each one is set off by how the board looks, and always gives a warning first.
• Supernovas. A big star that overheats (see below) is about to go supernova. It swells and throbs, with a dashed red circle showing the blast and red dots counting down the pulses. Round the star are two rings: send at least one ring out of the star and the solid red ring shrinks inside the dotted white one (it turns blue) and the star calms down. Otherwise it blows partway through the pulse after the last dot. Matter near it is destroyed and matter near the edge is badly damaged. The star's own threads go with it, but other threads survive.
• Overheating. From pulse 8, a full star that sits idle starts to glow red, more strongly each pulse. Sending at least half a ring out of it, or matter flowing out along its threads, cools it right down. Leave it for 4 pulses and it overheats. A small or medium star starts venting: it glows red and its matter visibly drifts away from it; it stops growing and loses matter every pulse until you send some out of it, or until it is nearly empty, when it settles and starts growing again. A big star starts a supernova warning instead: send at least one ring out of that star before it blows (the red ring shrinks inside the white one) and it calms down. Each side has at most one star venting at a time, with a short rest after each one. Supernovas only come from overheated big stars, never at random.
• Black holes. A supernova leaves a black hole for 3 pulses. Everything inside its dark circle is swallowed: the stars there go dark, and any matter that goes in is dragged to the centre and destroyed. Stay out until it closes. Threads passing right beside it snap.
• New stars. When the black hole closes, the stars around it come back and a fresh, unclaimed medium star is born at its centre. Be close by when it happens.
• Comets hunt long threads stretched across open space: the more of those you hold, the likelier one comes. A dotted path with drifting arrows appears across the whole galaxy one pulse ahead, through the long thread that drew it. During the next pulse the comet streaks right across along that path, cutting every thread it crosses and tearing apart travelling matter in its way. Matter on stars is safe.
• Nebula birth. Now and then a glowing cloud gathers in a big empty gap, roughly as far from both players. Two pulses later it gives birth to a super star with 5 rings and a golden halo: a prize worth fighting over. Its new threads can nudge the winning target up a little; the score bar flashes when that happens.
• Solar wind. Rows of arrows sweep across the board one pulse ahead. During the next pulse a wind blows, and anything sent drifts with it and is torn apart the further it travels: a short hop to a neighbour loses some, a long trip loses nearly everything. Matter on stars is untouched, and waiting out the wind doesn't make your stars overheat. Usually the best move is to hold still.
• Stardust storm. When too many stars across the galaxy are running hot, dark clouds gather over the hottest patches as a warning, each with a dotted edge. During the next pulse glittering stardust rain pours into them, destroying most of the matter under the heart of each cloud and less towards its edge; everywhere else is untouched. Stars it hits are scorched and stop growing until the end of the following pulse. Keep your stars cool, or use the matter under a cloud before it hits.
• Copy log copies a pulse-by-pulse record of the game. Paste it into the chat with Claude. The letters and numbers round the edge are the grid squares the log refers to.
• Undo takes back your last order while you're planning (or press Z).
• Pulses: the game is played in rounds. It pauses while you give orders. Press Space or Run pulse and both sides' orders play out together, slowly, and every move completes before the next round. The opponent's orders are hidden until then. Tempo sets how slowly a pulse unfolds.