How to play Supply Line

Crates of lemonade travel down a line of four companies to the customers: the factory, the distributor, the wholesaler and the shop. You run one of them; the computer runs the other three. Every week:

Crates arrive from the stage above you (the factory’s come from its brewhouse).
An order comes in from the stage below (the shop’s comes from customers), and you ship what you can. Anything you can’t ship is owed, and has to be shipped later.
You order from the stage above. Your order reaches them next week, and the crates take two more weeks to get to you, so what you order today arrives in three weeks, if they have it.

Every crate in stock costs $0.50 a week and every crate you owe costs $1 a week. The game is scored on the whole line’s cost over 26 weeks, not just yours, because in a real supply chain everyone pays in the end.

Medals

At the end we play the same 26 weeks twice more: once with the computer in your seat, and once with a careful planner that tries 108 settings of a good ordering rule and keeps the best. Bronze is beating the computer, silver is getting at least halfway from the computer’s cost to the planner’s, and gold is within 10% of the planner (and still under the computer).

Tips

Count what’s already on its way. The most common mistake is ordering again because the shelf is empty, when the crates you ordered two weeks ago haven’t landed yet. The “on order in all” box is there for this.
Base your order on what’s being asked of you, not on how you feel about your stock this week. Change it in small steps.
Owing crates costs twice as much as holding them, so a small buffer of stock is worth having.
The stages around you will overreact. When orders from below suddenly jump, ask whether customers really changed or the stage below is panicking.

The bullwhip effect

When the game ends, the chart shows every stage’s orders against what customers actually bought. Usually the swings grow at each step up the line: a small change at the shop becomes a flood and then a drought at the factory. That’s the bullwhip effect, and it happens in real supply chains for the same reasons it happens here: delays, each stage seeing only its own orders, and forgetting what’s already ordered. The lesson on it in our free How supply chains work course explains the causes and the fixes.

Questions

Is this the Beer Game? It’s our own take on the same idea. The Beer Game is a role-play that business schools have used since the 1960s to show how supply chains behave; Supply Line keeps its shape (four stages, delays, stock and backlog costs) with lemonade, simpler delays and the computer playing the other stages.

What does “share the shop’s sales” do? In practice games you can choose to see the customers’ orders and every stage’s stock each week, the way companies that share data do. It’s easier, and it shows why sharing sales data calms the bullwhip. Today’s chain is always played without it.

Where are my results saved? In this browser, along with a game in progress, so you can leave and come back.