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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