[MUD-Dev] Economic Growth (Was: [STORY] Story and population size)

Timothy Dang tdang at U.Arizona.EDU
Thu Dec 20 11:02:19 New Zealand Daylight Time 2001

On Tue, 18 Dec 2001, Bobby Martin wrote:

> My half-formed ideas regarding integrating NPCs into the economy
> are to have the NPCs know a local market price (by monitoring
> exchanges on the server) and scarcity.  For some default scarcity,
> they want to sell at e.g. 110% market price and buy at e.g. 80% of
> market price.

There's a potential pitfall of having NPC's price their merchandise
based on observed prices. If the prices considered are inter-player
observed prices, then players could possibly game the system through
fake trading.  It might be worth an hour of time for two players to
sell an item to each other back and forth in order to get a lower
(or higher) price on a valuable item they want to buy (or sell).

> If an item begins to be scarce, either in their inventory or in
> the local area in general, they simply raise their estimate of the
> market price by 10%.  If they are still selling at those prices,
> they raise the price still further.  Essentially, my hope is to
> arrange things so that NPC merchants virtually never sell out of
> an item unless they decide not to deal in the item any more.  The
> reason they don't sell out is that the price goes to infinity as
> their inventory goes to zero.

I've generally been down on trying to make NPC merchants active
economic participants, but at first glance I imagine something like
this could work because of player arbitrage. If NPCs each keep
separate measures of appropriate price, and adjust their own prices
independently of each other (which means using the individual NPCs
state, not the regional state, for information), any individual NPC
may get some prices out of whack.

However, if the prices get too out of whack, then you'd expect
players to arbitrage those prices between the different NPC
merchants. In order for this to work well, you'd probably need each
NPC to have unlimited stock and funds, though.

If done carefully, I don't see any way for players to game such a
system.  But it's easy to miss those things until its too late. One
minor detail is that you'd need to program trades with the merchant
so a player couldn't see that arrows are currently 100GP each, and
sell 100 arrows at once at that price. Instead, the merchant would
need to adjust the price-per arrow (or presented as total price) for
each new arrow offered to be bought (or sold).

You'd also want to make sure that no player or player faction had
control over access to any of the merchants. That way they couldn't
"starve" a given NPC for arrows to raise the price, since presumably
with open access someone would cheat and reap the benefits.

While I don't see ways to game it, it also could take some tuning to
make it work. For instance, how quickly do merchants adjust the
prices for different items? You probably don't want the per-arrow
price change to be as large as the per-palantir price
change. Possibly global information on scarcity could be used for
the adjustment rate. I imagine this will be tricky.

Timothy O'Neill Dang / Cretog8
One monkey don't stop no show.

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