Fifteen smudge pots. Light them at dusk and you lose $900.

Same fifteen pots, lit later: $7,465 more

Lit at dusk, it takes the bot 43 minutes just to walk all fifteen. The last one catches at 20:43. Four hours of oil each. By 00:43 every one of them is dry.

The first bud doesn't die until 02:53.

So $900 of pots burned dry two hours before the first bud died. At dawn: 78% bloom, the same as staying in bed.

Same pots, same blocks, lit when the air at each pot reads −1 °C: the first one catches at 02:20 and the last at 04:00. They burn straight through the hours that kill bloom. Net: $47,697. Two stars.

That's a $7,465 swing, and you didn't buy a single extra thing. The forecast shows you where the frost will land and about when it gets bad. It can't light a pot. You light them one at a time, on foot, and the hollow doesn't wait for you to get there.

The enemy goes where water would

On a clear, still night the ground loses heat to the sky, and the air touching it gets cold and heavy. Heavy air slides downhill. It fills the hollows first, then the bank along the road, and it sits there until the sun burns it off.

The game runs that on a grid. Every block (one 25-metre square of the map) has a height. Cold air levels across the low ground the way a puddle would, spills out where the hillside is open, and backs up where a road embankment dams it.

At dusk you get the honest forecast: the night run with nothing placed, drawn right on the map, with an hour-by-hour chart of the cold underneath it. Violet is where the bloom starts dying. Red is where more than half of it does. Hover a block and it tells you the low and the kill. Night 1's brief, from the game: The free air bottoms out near +1 °C at six, but the hollow below the big tree will sit five degrees under that.

Nothing is hidden. The cold doesn't roll dice. Run the same rig twice and you get the same dawn to the dollar, and the sheet tells you what went wrong: a pot that ran dry, a set stopped frozen, a pond that ran out.

Three tools, three catches

None of them shoots anything. You place them at dusk and they can't move. Then you walk out with a lantern and turn each one on by hand. You can't be at the hollow and the road bank at the same time.

Three nights, each one colder

Each night takes about three minutes at normal speed. F runs it four times faster. A frozen block is a number on the packing-shed sheet, never a game over, and R on the dawn sheet puts you back at dusk.

The water you can't turn off

Freezing water gives off heat. That's the trick. Keep a block wet and the ice on the bloom holds it at −0.5 °C, which is above where it dies. It's the best tool in the game and it has two rules.

In the game, start a set while its block still reads above +1 °C. (Real growers go by dew point; the game keeps one number.) Start it colder and the wet-down pulls the block down before the ice forms.

Then don't stop it until the block thaws after sunrise. Stop a frozen set at four in the morning and the ice pulls the heat out of the bud it was saving. On night 2 that one mistake costs $1,796 against par (the house's best night). Open every set at dusk instead and the pond runs dry while the blocks are still frozen.

If you've stood in an orchard at 3 a.m.

This is a game, not a forecasting tool. A small one: a 25-metre grid, one hill, three nights. Here's what it does encode.

• Bloom damage on the published full-bloom critical temperatures the game cites from Washington State University: 10% kill at −2.2 °C, 90% at −3.9 °C.
• Buds lag the air by about fifteen minutes. Damage only goes up.
• Wind machines need warmer air above the cold layer. When the air up there is below zero too, that's all they can bring down.
• Sprinklers protect through the heat of freezing, need a safe start, and burn the bloom if stopped frozen.

What it leaves out: wind, cloud, dew point, variety, bud stage, and what fuel costs this spring. It also bends three things on purpose. A pot warms the air out to about 57 metres, far past what one real orchard heater reaches. Every dead blossom comes straight off the sheet, when a real tree needs only a small share of its bloom to set a crop. And the dollars are a scoreboard, not a packout. Smudge pots are mostly history in real orchards; they're here because a pot that runs dry makes the timing plain. If you grow fruit and something in here is wrong, I'd like to hear it.

Free, ten minutes, and a keyboard

It costs nothing. No account, no ads, no download. It's one web page.

Time: three nights at about three minutes each, plus however long you stare at the dusk map before you commit.

A keyboard, for the full game. Placing the rig is a click, but the night walk is WASD and the space bar. On a phone, the box at the top of this page is the part you can play.