SWG uses what is called a faucet-drain economy. You can visualize a spigot of cash coming into the game, a big ol' sink where the money sloshes around, and a set of drains where the money goes out the bottom. When money comes in from the faucet, it's actually being "minted" - it's being created by the game system. The sink is basically the whole game. It's the bank accounts, the player inventories, all the money that is used for trades and transactions among players, etc. When money goes out the bottom, it's deleted from the system, rather than circulating back to a central bank.Link (via Terra Nova)
(Credits aren't the only thing that is generated, of course - a significant faucet into the game economy actually comes in the form of resource mining. Since the amount of money and the amount of resources coming into the game at a time both vary, you get small fluctuations in the price of resources as the value of both the resources and the currency changes. Plus, you also get different qualities of resources that affect the price. But we're not really talking about commodities pricing today, much as just about the value of a credit).
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