Guide
You run one factory's production line, racing two AI-run rivals for the same customers over 100 days. Buy raw materials, add or sell machines, borrow from the bank — and keep finished goods on the shelf when customers come, or they'll buy from someone else. The whole game is Little's Law made playable: the last section spells out exactly how.
Starting a game
Every company starts identical: 5 machines, $20,000 in cash, no debt, and a 33.3% share of the market. Leave the seed blank for a fresh game, or enter one to replay exactly the same days — same demand, same rivals — and see whether a different plan does better. Click the level in the header to see the game's seed, for example to check it's the one your professor assigned.
Levels
- 1 · Training: capacity has to lead demand
- Demand grows steadily from 12 to 30 units a day. Add machines before you need them, financed sensibly, and don't buy more material than your line can process.
- 2 · Seasons: build inventory ahead of the peak, or build the capacity for it
- Each game draws a pattern: a seasonal year (slow autumn and winter, brisk spring and summer) or a quiet year with a rush at the end. The board shows the pattern and the demand ahead. Machines arrive 10 days after you buy them, so capacity bought when the peak arrives comes too late. Owning a machine costs $5.00 a day, idle or not, and every unit of inventory held overnight costs $0.10. And customers leave twice as fast on days you can't deliver.
- 3 · Real Life: variability needs buffers
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Everything from Seasons, plus what goes wrong in real operations. Each game draws its own
conditions, and the board shows them:
- Machine speed. A machine may take up to 2 days to process a unit instead of one. Slower machines mean a longer cycle time, so you need more of them.
- Late deliveries. On some days your materials don't arrive. A pop-up tells you, and the delivery comes on the next good day.
- Prices and the bank's rate. The sale price, the material cost and the bank's interest rate vary from game to game.
Reading the board
Material flows left to right: from the material suppliers, through each company's line, to the customers. Your line is outlined in green; the two rivals sit above it. Each line has three columns:
- Raw materials
- What you've bought and haven't started on yet. The one place a backlog builds before production: buy faster than your machines can work and it piles up here, tying up cash.
- Processing
- How many units your machines worked on today — never more than your capacity, and never more than the raw materials on hand to feed them. A machine with nothing to work on stands idle; beside your machine count, the board shows how many stood idle today for lack of materials.
- Finished goods
- Units ready to sell. Customers buy from here; if it runs dry before they're satisfied, you've failed that day's demand.
The gear in the top of each Processing bar turns while its machines are working and stands still when they're idle. After each Advance 1 Day, the bars replay the day, left to right: what moved on slides to the next station (only as much as the machines took, or customers bought), then each bar refills to today's level. Materials left waiting in front of the machines are what make your cycle time grow: that's Little's Law. The header's Motion switch stops the movement.
Beside each line: machines and capacity, cycle time, and — for your line only — cash and debt. The bar along the bottom shows the unit economics, everyone's sales today, and how far through the 100 days you are.
Daily purchase
Your main lever. Set how many units of raw material to buy each day, then press Set daily purchase: the slider alone doesn't save it. Until you press it, the button turns amber and the line underneath says the old number still applies; once pressed, it reads "✓ Set. Buying 12 a day". Each unit costs $35.00 and sells as a finished good for $65.00. You only ever buy what you can afford that day. Everything after the purchase is automatic: machines pull from raw materials, and whatever they process becomes finished goods the same day.
Machines
Machines set your capacity. At Training and Seasons each machine processes 1 unit a day; at Real Life a machine may take up to 2 days per unit, so the same machines process fewer units a day. A new machine costs $10,000; selling one returns only $5,000. Buying capacity you don't need and selling capacity you'll want back are both expensive mistakes.
The Bank
Borrow and repay in steps of $5,000. Your credit line is 70% of your machines' value — $35,000 with the starting 5 machines — and it grows or shrinks as you buy or sell them. Interest is 10% a year, charged daily in cash, and so are running and holding costs at Seasons and Real Life. Your materials are bought first each day, and can use up all your cash; if nothing is left for the interest and running costs, the bank sells your machines at the resale price until they're paid — losing far more capacity than the bills were worth. Beside your cash, Covers N days of costs says how long it lasts at today's pace (materials, interest and running costs) before any sales come in, in amber below three days; below one day it tells you to buy less or borrow. A pop-up says when your purchase was cut short for lack of cash, another warns you the first day your cash is falling fast, another tells you when a machine has been sold, and the debrief counts any machines lost this way.
Demand and market share
Total demand grows over the game, from 12 units a day at the start to 30 by the end, and swings up to 25% either way on any given day. Each company's customers are its market share of that total.
Fail to fill your customers' demand on a day and you lose 0.5 points of market share to whichever rivals did fill theirs. On a day when everyone falls short — or no one does — nothing moves. Lost share only comes back the same way: on a day a rival falls short and you don't.
Your competitors
Each rival runs on its own habits, set at the start of the game: some buy lean, just enough for today's demand, others keep a buffer; some add machines readily, others hesitate; some lean on the bank sooner than others. You can see their lines and market share, but not their cash or debt — read their habits from how their columns move.
Advancing the day
Advance 1 Day runs everyone's day in order: the rivals make their decisions, every line buys and processes, the bank collects interest, customers buy, and market share moves. Your controls act immediately, so make your changes before you advance.
Game over
After day 100 the company with the most final equity wins: cash plus machines at full price, minus debt. The debrief ranks all three by it and shows their final market share alongside — share keeps your customers coming, but it isn't the score. Your Stats page counts a win the same way. Replay the seed to try a different plan against the very same days.
Little's Law, in this game
Little's Law says that for any process, work in progress = throughput × cycle time. Here:
- Throughput
- → Units your machines complete a day, capped by capacity: machines × 1 a day at Training and Seasons; at Real Life, machines ÷ the days each takes per unit.
- Work in progress
- → Everything in the line: raw materials waiting for a machine, plus what the machines are processing today.
- Cycle time
- → Days from purchase to finished goods. Never set directly — it's work in progress ÷ throughput, shown beside each line. A line that keeps up runs at 1 day.
Push more material in than the line can process and the extra doesn't come out faster — it waits, in raw materials, costing cash, and your cycle time climbs: ten units waiting in front of a line that finishes five a day means three days from purchase to finished. Starve the line and throughput falls, finished goods run dry, and customers leave. The game is finding the flow your capacity can actually sustain as demand grows, and adding capacity before you need it, not after.