You may think that when you spend time in online game worlds such as Everquest or Star Wars Galaxies, you are just enjoying yourself.
By Mark Ward
BBC News Online technology correspondent
But analysis of how long people spend in the games and what they do there has shown that game-playing has a significant economic value too.
Gaming has economic value too, even if it is virtual
According to the analysis this gaming activity has a gross economic impact equivalent to the GDP of the Southern African nation of Namibia.
The data came out of a follow-up to a pioneering study that tried to find real world economic measures of all the activity in so-called massively multi-player online role-playing games (MMORPGs).
Edward Castronova, now associate Professor of telecommunications at Indiana University, carried out the original study which measured the economic productivity of each Everquest player.
It found that a worker in the game's kingdom, Norrath, was just as productive as a worker in Bulgaria.
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Prof Castronova found that, on average, a typical person spending a typical hour in Everquest produces goods and services roughly equivalent to the value of goods and services produced by a typical Bulgarian spending a typical hour in Bulgaria.
Now a follow-up analysis has shown that online gaming in virtual worlds also has a total economic impact just as big as some real countries, although smaller ones than Bulgaria.
The new study focuses on productivity and the total output of all the people that play MMORPGs.
Typically players of Everquest and other online games create characters that take on a profession relevant to the virtual setting.
Everquest is populated by warriors, magicians, priests and thieves. As well as looting saleable items, many characters take on a profession and, as they build up skill in that trade, produce virtual goods for trading.
Prof Castronova assumed, based on his earlier study, that the average gross domestic product of each of the two million or so permanent virtual world dwellers is $2,000 (£1,087).
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This figure measures the monetary value of the things, such as magic weapons and trade goods, that users produce during the 20 hours per week they typically spend in the online worlds.
The calculation ignores the subscription revenue that people pay to play the games.
Prof Castronova said this calculation produces a more realistic figure of the economic impact of gaming in virtual worlds.
He said the real world nation with an equivalent GDP per capita and population is Namibia which has about two million people and, according to World Bank figures, a gross national income of $1,790.
The country that the online game world could take over next is Jamaica.
"I thought it might come out to be equivalent to the GDP of a small island nation," Prof Castronova told BBC News Online.
Online gamers have a GDP bigger than Namibia
"Namibia and Jamaica are much heftier countries than that. So, yes, I was a bit surprised.
"When you realise the immense cultural impact that a place like Jamaica has had," he said, "you also realize the potential impact that virtual worlds might have."
"The deeper point is that virtual worlds simply are not trivial phenomena," said Prof Castronova. "Statistically, they matter, already, and it's only 2004."
Some of the games with large populations, such as Lineage that has about four million players, could already equal the GDP of a smaller nation all by themselves.
He said the current set up of playing to produce stuff to trade is likely to last and help to steadily grow the economic impact of online gaming.
"We are learning that people get deep enjoyment from building up a stock of goods out of nothing," he said.
Players like going out and finding iron ore, smelting it into iron, hammering it into a sword, selling it for some gold pieces, so they can buy new clothes.
"Each of those steps is emotionally satisfying," he said. "Economics is fun. And everything that is fun will stay in games, without question."