How Moon Miner builds a Moon out of one number

Under the hood · the world is calculated, never stored

Moon Miner hands you a mining pod and a Moon full of rock, ore, caves and gas pockets. None of it exists as a map. There is no file anywhere containing the layout of your Moon. There is one number, and everything else is worked out from it as your drill arrives.

That number is called a seed. When you start a new world, the game picks a random whole number and keeps it. That single value is the entire Moon.

Every tile is a calculation, not a lookup

The Moon is a grid of tiles, fifty four across. When the game needs to know what a particular tile is, it does not look the answer up. It calculates it, from three inputs: the seed, the tile's column, and the tile's row.

The tool that does this is called a hash. A hash takes some numbers, scrambles them thoroughly with multiplications and bit shuffling, and spits out a result that looks completely random. The important part is that it is not actually random at all. Feed the same three numbers in and you get the same answer back, every single time, forever. That property is called determinism, and it is what makes the whole trick work.

So the question "is there ore at column 12, row 340?" has an answer that costs a few arithmetic operations to produce and nothing at all to store. Ask it a thousand times and you get the same answer a thousand times.

Where the ore goes

Pure hashing would sprinkle minerals evenly across the rock like static on an old TV, which would be boring to dig. Real ore comes in veins.

So the game layers a second thing on top: a noise field. Noise here means a smooth, rolling landscape of values, high in some places and low in others, generated from the same seed. Wherever that field rises above a set level, the game declares that patch of rock to be a vein, and then fills roughly two thirds of the tiles inside it with minerals. Because the field is smooth, vein patches come out as connected blobs rather than confetti.

On top of that there is a flat chance, roughly one tile in nine through the whole upper half of the Moon, for a lone mineral anywhere in solid rock. Those scattered singles are actually the bulk of what you dig up. The veins are the payday.

Which mineral you get depends on how deep you are. The Moon is divided into eight layers running down to 760 metres, and each layer has two headline minerals of its own plus a smaller share of the two from the layer above, so the boundaries blend instead of snapping. The three deepest layers also cut the spawn rate hard, down to a quarter of the surface rate at the bottom, which is why the deep pays better per tile but hands you fewer of them.

How the caves get carved

Caves use an older and stranger technique. The game starts by marking roughly forty six percent of tiles as open, purely at random from the seed. The result is meaningless noise. Then it applies one rule, four times over: look at the three by three block of tiles centred on each tile, and if five or more of those nine are solid, that tile becomes solid too. Everything else becomes open.

Run that rule once and the noise gets slightly clumpier. Run it four times and it settles into smooth, rounded caverns with real walls and passages, as if it had been carved. Nobody drew those caves. They fell out of a rule that was applied until it stopped changing much.

What the save file knows about the Moon

The payoff for all of this shows up when the game saves. The Moon is 54 tiles wide and 796 rows deep, which is 42,984 tiles. Your save describes none of them.

It records your credits, your upgrades, your cargo and where your pod is, the way any game would. The entire world, though, comes down to two things: the seed, and one bit per tile answering the only question the game cannot recalculate, which is whether you have dug there yet. One bit each across 42,984 tiles is 5,373 bytes, and that is before it gets compressed by squashing long runs of untouched rock into a single entry. Load the game and it regenerates the whole Moon from the seed in an instant, then paints your tunnels back on top.

Your dug tunnels are the only part of the world that is genuinely remembered. Everything else is re-derived on demand.

Does the Moon have a bottom?

It does, and it is closer than the endless-feeling rock suggests. The eight layers run out at 760 metres. Below them sits a core chamber, playable down to about 776 metres, and under that a thin band of root tiles and then bedrock. That really is the end of the world.

What sells the illusion is not endless generation. It is that the root floor cannot be drilled. The game gives it infinite hardness, so no drill in the game will ever break through it and nobody ever reaches the seam where the rock stops being invented. A wall you cannot pass looks exactly like a world that goes on forever.

One last consequence of building a world this way: because it is a pure calculation, two people with the same seed get the same Moon. Same layers, same caves, same veins, same gas pockets, in the same places. Not a copied map. The same sum, worked out twice.