Suppose they gave a marketing campaign, and everybody came?

Back in September, Hasbro launched Monopoly City Streets, a massive multiplayer online game that transforms Google Maps into a globalized version of the well-known board game. In the run-up to Christmas, the online game was supposed to promote a boxed version of the game that Hasbro sells for $40 list.

Three months on, however, Hasbro’s MMOG – constructed by ad agency Tribal DDB working alongside engineers from Google Maps – achieved something unexpected. It became vastly more popular than anyone expected. Monopoly City Streets now ranks as the world’s 12th-largest example of the genre, according to Matt Ross of Tribal DDB, attracting 15 billion page views a month.

Presenting his agency’s campaign at last week’s Creativity and Technology conference in London, Ross announced: “We’re trying to invent things that are useful to people. We never know if our stuff is going to work.”

“Now Hasbro don’t know what to do with it," Ross said. "They have a kind of new product on their hands.”

Unexpected popularity has had unintended consequences for Hasbro. If it scraps the game next month, as planned, it risks alienating 1.5 million registered users. If it allows it to continue, it will need to find a way of monetizing all of those eyeballs that may cannibalize buyers of the game they want to sell who are happy enough with the online version it was supposed to promote.

Oh yeah — Ross also noted that his agency's wildly successful campaign was achieved with “precisely zero media spend."

Interesting things happen when advertising slips the moorings that have traditionally bound it to Big Media. In particular, Hasbro’s dilemma underlines the fact that the message-carrying capacity of traditional media has always been constrained. As a result, media owners have always carried promotional messages to audiences on a time-limited basis.

The cost of traditional media doesn’t decline appreciably during a campaign. Accordingly, the cost of reaching new consumers increases exponentially as a campaign proceeds. The risk of over-exposure increases, too.

Hence the advertising industry’s traditional ability to take pride in brilliantly crafted, but transient, promotional efforts.

So what happens when scarcity-based constraints disappear? What happens when advertisers and their agencies produce their own campaigns and distribute them on the web?

Attitudes change. As permanence becomes a possibility, pride in transience starts to look questionable. The ad campaign that Hasbro thought it was buying from Tribal DDB may yet turn into an enduring product. In a similar vein, Anders Gustafsson of Crispin Porter Bogusky Europe told last week’s conference: “The stuff we’re doing should last for years, not months.”

Several years after adland produced its first throwaway virals, this suggests that something much larger than frustration with search engines lurks on the horizon for Big Media.

For a century or more, the advertising industry and Big Media have operated on the basis of mutual dependence. Big Media offered unusually broad reach and attracted big budget creatives as a result. In adland, watching your creatives play out across major media was always a mark of high seriousness.

Now this historic pact is coming under pressure. In places, it has started to unravel. The crude appeal of banners and buttons remains important, but long ago ceased to be at the center of the digital action. For marketers who need to engage massive audiences, the web offers a genuine alternative to press and TV, one that allows advertisers to create their own content.

With no small sense of irony, last week’s conference of digital creatives took place at the galleries constructed by Charles Saatchi out of the elegant hulk of the Duke Of York’s barracks in Chelsea.

Yet the Big Media outlets that carried Saatchi’s inspired advertising copy three decades ago merited barely a mention. Among other things, delegates were asked to consider what might start to happen when we, our devices and the built environment become seamlessly networked.

Adam Greenfield, head of design direction at Nokia, describes one possible outcome: an urban landscape filled with “dynamic advertising that covers every surface and knows everything about us”. He talks of a “shroud of awareness” surrounding shoppers and pedestrians with “dynamic advertising” constructed on the basis of “sensor readings that record place, time and event”.

The future of outdoor advertising has rarely looked so full of potential. The future of Big Media has rarely looked so marginal.

Kevin Slavin, another speaker at last week’s conference, lectures alongside Greenfield at New York University. He is also the co-founder of Area/Code, a New York-based hotshop that develops games on behalf of agencies and advertisers.

According to Slavin, “the idea of being able to see the value of everything all at once” is “grinding down” the price that retailers in particular can charge their customers. “Meaning," he claims, is shifting from physical products to the “informatic layer” embodied in devices and networks.

This isn’t a particularly controversial notion. What is controversial is the conclusion drawn by Slavin: “If you’re in the consumer packaging and branding business, you’re fucked.”

Perhaps. But ubiquitous computing also represents a further threat to the historic pact between adland and Big Media. In the not-too-distant future, the cereal packets that contain my daughter’s Coco Pops may carry a cheap screen, wirelessly connected to the web, that plays cartoons across the breakfast table. As a result, BSkyB, the BBC and ITV will lose access to eyeballs.

Disintermediation of this kind is already a reality in some shopping malls, where retailers have started sending promotions to handsets carried by approaching shoppers. According to one analyst firm, 35 start-ups and established companies across Europe are developing technology for use in such digital proximity campaigns.

This won’t result in the death of retail advertising in the weekend editions of national newspapers any time soon. But there’s more to come. The next steps involve the gradual splicing together of three separate disciplines: mobile advertising technology, real-time search and the long-established science of retail footfall analysis.

Coincidentally, Twitter this week released its long-awaited geolocation API into the wild. In this context, one statistic is worth noting: according to the digital ad agency Razorfish, 44 per cent of US consumers who follow a specific brand on Twitter say they do so in order to gain access to special offers.

Campaigns that cut out Big Media with a mix of gaming, location awareness and social networking aren’t yet an established fixture in adland. But we might not have to wait too long. The iPhone’s crystalline screen was made for opportunities like these.

The fallout could make Rupert Murdoch’s dispute with Google look like the proverbial storm in a teacup.

Among the digital creatives who gathered together last week, a few are already looking toward the future. “Now that we've been invited to the party and have money, influence and power,” said Ian Tait of Poke London, “I worry we are like a bunch of kids with the keys to the sweet shop.”

Judging by the heady optimism on display at CaT last week, Tait’s concerns aren’t yet widely shared by his peers. But they will be – and soon enough. As Google knows all too well, disruptive power brings serious responsibilities in its wake.