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You're running a small factory. Pieces move through several stations; at each one, a worker does a step of work. Your job is to make money: you earn revenue when good items reach the customer, and you pay for labour, materials, and holding inventory. If your cumulative profit hits zero, you go bust.
Important rules: each station has a cycle time and works in batches; items can be defective (e.g. wrong spec, poor quality). The customer only accepts good items — defects that reach them cost you heavily (returns, recalls, lost trust). From time to time the "market" changes: customer preferences shift, and some in-flight work can suddenly count as defective. Watch the P/L, the flow of pieces, and what gets accepted or rejected.
This simulation builds up the Toyota Production System (TPS) — Lean — one step at a time. TPS was developed at Toyota from the 1940s onward (Ohno, Shingo, and others). It isn't only for cars; it's a way of thinking about any flow of work: the customer defines value, and we aim to produce more value with the same people and materials. The goal is not cost-cutting by firing people; it's eliminating waste and making quality and flow visible so we can improve. In the next steps we'll see a "before Lean" situation, then add one principle at a time so you can feel how each change fixes a problem you've just seen.
Run simulation to see Profit & Loss