Choose what goes in the hall.
You have a plot of lunar surface at the rim of a lava-tube skylight, and a colony that needs feeding. Pick a tool on the left, then click — or drag — on the ground. Raise grow halls, sow them, keep them watered and fed, harvest before anything wilts, and spend the proceeds on the hardware that gets you through the night.
Everything works by finger. With a build tool up, drag one finger to pull out a hall or run a road; with any other tool, one finger drags the map about and a tap uses the tool on whatever you tapped. Pinch with two fingers to zoom, and slide them together to move as you zoom. At the widest zoom the whole plot already fits, so the map deliberately stays put until you zoom in.
Take the Grow Hall tool and drag a rectangle across open ground — the outline shows the size and the price as you go, green if it will fit and red if something is in the way. Let go and the hall goes up. A hall is one field: it takes a single crop across its whole floor, and cost, yield, lighting draw and water all scale with how many tiles you gave it. Halls can be anything from a single tile up to eight a side, so you can put a small research hall next to a sprawling potato barn.
Both are laid by dragging. Press on the tile you want to start from, drag to where you want to finish and let go: the run follows the longer axis first and turns once, the way a road tool has behaved since SimCity. The preview shows every tile green where it will lay and red where something is in the way, with the running cost at the far end. Anything blocked is simply skipped and you are not charged for it. A single click still lays one tile.
A hall or module has to touch a regolith track that leads back to a habitat, or the crew cannot service it properly and it grows at about three-quarters speed. Lay track as you expand — it is the cheapest thing you can build. Unserviced modules show a red pip.
Rail Line does the same job and more. It carries service like a track, and any hall whose outline touches it gains a tenth again in throughput, because the crop leaves by the wagonload instead of being carried out by hand. Lay a few tiles in a row and freight trains appear and work the line on their own — they need somewhere to go, so a loop or a long spine runs better than a stub.
A lunar day runs about 29.5 Earth days: roughly fourteen and a half sunlit, then the same again in darkness. Solar arrays give you nothing for two weeks at a stretch. A legacy radioisotope unit covers baseline life support but not the grow lamps, so power is shed one whole hall at a time as the batteries drain. Battery banks buy you a few halls through the night; fission surface power ends the problem for good.
A hall you have just raised is floored with sharp, sterile dust: no structure, no biology, nothing that holds water where a root can reach it. Fresh beds grow at about two-thirds the rate of conditioned ones, and the meter on a selected hall shows how far along they are. Every harvest works roots and stubble back in and moves them on — faster once the biomass oxidation loop is running — or you can pay to condition a hall outright with imported biomass. Bulldozing a hall throws that work away, so it is usually cheaper to replant than to rebuild.
Build a Broadcast Studio and the farm starts paying its own way between harvests. Every day it files what it has: the crop standing in the halls, the crew at the mess table, a flower crop being cut and arranged. Earth pays a fee on delivery — that is the floor that keeps you solvent while a potato takes three months — and pays again on the audience the programme has built.
The audience is the part that rewards variety. Every subject carries a novelty that collapses the moment it airs and recovers slowly over the following fortnight. Show the same potato every week and the fee shrinks and the audience drifts away; keep a dozen different things standing in the ground and there is always a fresh one to lead with. A farm that grows one crop very well earns roughly half what a farm growing twelve indifferently does. That is deliberate: the camera is how biodiversity pays for itself.
Not everything in the catalogue is a plant. Oyster mushrooms fruit on the spent straw and stover that every harvest leaves behind, and they need no lamp at all — which means they keep producing straight through the fortnight of lunar night, when every lit hall is being shed one at a time. They also respire: they burn oxygen and hand back carbon dioxide, the reverse of a canopy, which quietly refills the buffer an exporting farm runs down. Yeast and rhizobia work the same way. Cyanobacteria fix their own nitrogen and return it to the nutrient tanks.
Watch the residue figure: it is what the cultures eat, and it only comes from harvesting something photosynthetic. A farm of nothing but mushrooms starves.
Sow every conventional crop in the catalogue at least once and the Biotech Lab opens in the Research tab. Each engineered line is a real crop carrying real traits — improved harvest index, biofortification, a photorespiratory bypass, faster relaxation of non-photochemical quenching, extended bloom, radiation tolerance, reduced stomatal density, perchlorate tolerance, a shortened cycle, molecular farming — and the catalogue tells you what each one does and what it is based on. They cost credits and science to develop, and their seed is dearer for ever after. They are also the only way to keep a farm growing once the conventional roster has stopped surprising anybody.
Everything you harvest is banked as an accession: a line held in living store. The goal of the station is not the farm — it is the Lunar Seed Vault, sunk into the lava tube through the skylight the settlement was founded on, where the rock holds one temperature and tens of metres of basalt stop what no surface structure can. Get the oxidation loop running, bury the modules under regolith, bank twelve accessions, and it can be signed off. After that it pays a slow dividend in data on everything it holds, and a line kept in the vault can be re-sown from secured stock when a tired-seed year would otherwise ruin it.
The ledger is at the top of the Goals tab. The target is every line the farm can grow, plant and microbe alike, held against the possibility that somebody will need them.
Plants make oxygen and consume carbon dioxide; the crew do the reverse. A surplus farm exports carbon inside the food it sells, so the buffer runs down over time — watch the CO₂ figure, build the biomass oxidation loop, and buy a cylinder if it gets tight. Water is recycled at about eighty percent; the rest comes from resupply or from cooking hydrogen out of regolith.
The bar along the bottom of a hall is growth. Coloured pips along the top mean, in order: green for ready to harvest, yellow for fungal infection, blue for dry, purple for starved of nutrients, red for no track connection. Select any module to see the full picture.
An original game, written from scratch. It owes its shape to Maxis' SimFarm (1993), but shares no code or art with it. The crop roster is drawn from plants that have actually flown or are long-standing candidates for bioregenerative life support; the numbers are tuned for play, not for publication.
The catalogue photographs are openly licensed — public-domain NASA imagery of the crops that
have actually been grown in orbit, and Creative Commons photography for the rest. Every one is
credited by source, creator and licence inside the catalogue and in
img/CREDITS.md. Engineered lines are illustrated with their conventional parent's
photograph and captioned as such: there is no photograph of a cultivar that does not exist.