I'm trying to use stocks and flows to create a model for my transportation game. Stocks correspond to nouns and flows correspond to verbs. At first I thought businesses would be stocks and the transportation of goods would correspond to flows. But I could also see the businesses as flows (since they consume and produce things) and the cargo areas and trucks as the stocks. Or maybe both trucks and businesses are flows, and only cargo areas (loading docks) and warehouses are stocks. Or maybe the cargo itself is the stock.

When it comes to a game, the player's decisions (and the AI's decisions) can directly affect flows, but not stocks. You can change the rate of production in Warcraft by hiring more peons, researching technology, etc. Production of gold is a flow. You do not directly change the amount of gold you have (except by buying something, but I think that's an instantaneous flow). Gold is a stock. There's no decision to be made with a stock—it just exists. There is a decision to be made with each flow, because you can throttle it back from its maximum. There are other decisions to make as well, but the basic resource management decisions (for gold, wood, soldiers, etc.) are about flows, not stocks.

In my game, the player controls the movement of trucks and the AI controls the businesses. The decisions are based partly on how much of each resource is available. I'm planning to treat trucks as stocks and the loading/unloading of them as flows. Businesses will be flows, but their cargo areas will be stocks.

The transfer of cargo is not enough to make an interesting game. The player will also need to make decisions about infrastructure and placement of transportation systems. The actual loading and unloading of trucks is boring; it's likely that an AI agent, acting on behalf of the player, will make those decisions. I still don't have a clear idea of where I'm going with this game, but it's already led me to some interesting topics (operations reseach, system dynamics, supply chain management).


1 comment:

Unknown wrote at March 15, 2007 12:15 AM

It does bring to light some interesting ideas. I once thought of a game similar to the Incredible Machine which serve a purposes as a physics simulation for building organizations. Instead of water in the stocks and flows metaphor, it's money.

Like in the Incredible Machine, different money machines (IRAs, Money Market Accounts, Stocks and Bonds) would be represented by these physical machines. You could tie in real stocks to the representations, for instance, to create money market simulations on live data. This is one way of visualizing money and monetary machines.

It would be interesting to watch such a machine in action with live data. Like any game-like interface, plugging different machines in would be an interesting way of determining if you are good at making money. Of course, sometimes the "stocks and flows" metaphor isn't exactly adequate to describe more complex money 'machines', some of which wouldn't necessarily represent a 'stock and flow' element. Sometimes plants or trees are the metaphor, like 'Money Market Growth Funds' -- but this metaphor does not equate to "stocks and flows", but equates to farming.

There is also processes of business, like inventory and logistics, which are like gates. These gates have costs associated with them. This more closely represents a peeler, which would peel an apple, where the apple would represent the commodity, and the peeling of the apple would represent a loss in profits after logistics takes its toll on a product. This could also equate to 'rotten apples' -- or apples with worms in them, ie: products that never make it to the end of the logistic pipeline.

Anyway, great idea Amit, always a pleasure to read musings on game ideas and on simulacra in general.