Sexual orientation, private debt, medical records, even your favourite ice cream flavour: do you know much of this personal information is out there and available for sale?
And what if it could affect your job applications, whether you can rent a house or how high your insurance premium will be?
A new Austrian-designed online game titled "Data Dealer", set for launch this week, hopes to make people a little more aware of their exposure to these risks, even if at a minimum it prompts them to switch off the GPS application on their smartphones.
"(Companies) are collecting more and more personal data," designer Wolfie Christl told AFP. "At the same time, people are bored with thinking about this... so we had the idea to make a game out of it."
A colourful demo was released last year, and "Data Dealer"—a browser game in the same style as Facebook's popular "FarmVille"—won the Games for Change "most significant impact" award in New York in June.
"Here's the most amusing way to learn the depressing news about your vanishing privacy," Forbes magazine commented.
Some 80,000 players have already tested the game, which received funding from the Austrian government and the City of Vienna and will be available online for free.
"I don't think most people can really imagine what it means not only to collect but also to collate and to combine all these massive amounts of personal data," said Christl, one of the game's four core designers.
Even "really boring" information can be a goldmine, the cheerful young designer added.
That is the premise of "Data Dealer".
Players get to collect thousands of profiles at the click of a mouse, using shady characters such as a Bernie Madoff-lookalike and a disgruntled nurse who has no qualms about selling patients' records to supplement her meagre salary.
The characters are colourful and amusing. But the scary bit is the message behind the game.
For a few hundred euros (dollars), the manager of a tanning salon will hand over his client list, including names, birthdates and email addresses. Loyalty cards reveal diets and buying habits. A dating site profile turns up a person's relationship status and even the age when they had their first sexual encounter.
The player can then sell this information to a major employer, a rental authority or a security agency to make a quick buck and expand his or her virtual empire.
"Data Dealer" is just a game, but what if fitness-monitoring systems such as Nike+ sold information to your health insurance provider: would your premium go up if you failed to run a required distance per day?
"People don't know about the value of this personal data and they also don't control it," Christl said, adding: "If we want to have a positive future digital society then we really need to enable people to make the self-determined use of personal data and get back control of it."
The City of Vienna's creative agency Departure praised "Data Dealer" as "the most innovative international approach to... data protection and online media competence".
"A game will probably not make a big difference, but it is a building block," Tassilo Pellegrini, communications expert at St. Poelten technical college, told AFP.
"Data Dealer can boost people's awareness, and with more awareness they might then act differently."
Mass surveillance and privacy concerns became a major issue this year after US whistleblower Edward Snowden revealed the extent of the US National Security Agency's spying on civilians.
Last week, the UN General Assembly's rights committee passed a "right to privacy" resolution, which found that surveillance and data interception by governments and companies "may violate or abuse human rights".
For Christl, who has been working on this not-for-profit project with a small team for two years, the Internet is still a great communication and innovation tool.
But he hopes "Data Dealer" will make people pay more attention to their privacy settings.
The team is now planning an educational version of the game and is working with schools and digital literacy programmes.
Developments in the news will be regularly inserted into the game and a later version will even allow players to hack into each other's accounts for an even more realistic effect.
As Christl put it: "It should also be entertaining; it's not about preaching."
Explore further: UN resolution aims to protect right to privacy