Chapters * Title * Contents * Introduction * Place * System * Design * Using * Future * Bibliography
Sections
* Design * Two_Simple * Sell * MULE * MULEvsMarketPlace * Incentives * Trade_Dependence * Symmetric_Commodities * Illustrating_Externalities * Showing_The_Model
MULE: The Starting Point
The game that most strongly influenced MarketPlace was MULE (Bunten, Bunten, Rushing, and Watson, 1983). Written for the 8-bit
microcomputers of the early eighties, MULE was a design triumph but a commercial failure. MULE places four players in the role
of settlers of a new planet. The game contains:
* resources in the form of plots of land that are developed by placing production units upon them,
* which units produce one of several commodities (food, energy, or ore) according to rules of diminishing returns. The
commodities are sold to other players or a computer-played store at auctions,
* producing funds that players use to purchase more commodities and production units.
* The central store acts as buyer and seller of last resort--setting limit prices for the sale and purchase of commodities. It
also acts as the sole manufacturer and seller of production units.
Players are given a limited amount of time per turn, which they must pay for with food. Moves in the basic game include
installing production units on land plots and changing what production units produce. Non-energy production units require
energy to function. Ore units are used by the central store to manufacture more production units. MULE is scored cooperatively
and competitively. Players are granted points for the commodities, cash and production units they own at the end of the game.
If the colony as a whole scores higher than a threshold level, the top player is said to win. (If the colony is below the
threshold they are collectively told off by the game--discouraging the top scoring player from boasting to anyone.)
Experiencing Markets and Market Failure in MULE
MULE demonstrates how a market can generate changes in resource allocation in response to changes in price. Underproduction of
a commodity leads to a rise in the price offered at auction, which leads players to shift into producing that commodity.
Lemonade-Stand Capitalism
MULE thus models a classic simple economy--sometimes called lemonade-stand capitalism. Players start with equal market power,
have perfect information about the products they purchase, and there are no side effects (externalities) of production or
consumption.
Volatility and Monopoly
The MULE economy is volatile to only a limited degree. The small number of players ought act more like large firms than the
large number of classical economic actors, any one of which is too weak to influence prices. Players may be able to corner the
market in a commodity, driving the price up. However, players are limited by the actions of the central store and the limited
elasticity of demand. Even given these limitations, one of the limiting factors on efficient market function can be
found--monopoly.
Greg Kimberly/gregkimb@gak.com