TurfMaster Pro

You inherit a house in Willow Creek Estates, Denver, with a sprinkler system installed by “a guy”. The job is to keep the lawn green from April 1 to November 15 without running out of money, collecting HOA fines or wasting water. The interface looks like professional irrigation software, with ten views covering zones, sprinklers, hydraulics, scheduling, weather, soil, reports, diagnostics and automation.

What’s simulated

The yard. Every 2×2 ft patch (4,000 cells) has its own soil, elevation, shade, moisture, root depth, nitrogen, thatch, weeds, disease, grubs and grass species.
Hydraulics. Static pressure follows neighborhood demand, and Hazen-Williams friction losses are computed through the meter, backflow preventer, valves and laterals. Radius depends on pressure, and wind pushes the spray off course.
Heads. Each nozzle has its own distribution profile. Heads clog, tilt, break, get buried by thatch and get blocked by tall grass.
Weather. A Denver-like climate with heat waves, hail and early freezes. Evapotranspiration uses Hargreaves ET₀, and forecasts improve as the day gets closer.
Society. The HOA inspects every Monday, drought stages restrict watering days, a water-waste patrol writes citations, and water is billed in tiers.

A 3D view of the house and yard with sprinklers running — The optional three.js site view, with zone 2 running.

Balance

The season is tuned against five scripted play styles that run in Node over several seeds. Neglect scores about 31 and freezes the pipes every time. Casual play lands around 57. An expert who fixes the inherited layout (matched nozzles, cycle and soak, a morning schedule that ends by 10 AM, a blow-out before the hard freeze) averages about 87.

A certified letter from the HOA with an annotated black and white photo of the lawn — The HOA sends photographic evidence. The photo is black and white.

How it’s built

Vanilla JavaScript with no runtime dependencies and no build step, apart from three.js for the optional 3D view. The simulation files don’t touch the DOM, so the same code runs headless in Node for the test suite, the balance runs and a long-play soak test. All the brands in the game are made up.