Qatar Airways is currently running a treasure hunt promotion during their Travel Festival, offering a free flight to a mystery location. The Willy Wonka-esque Golden Ticket giveaway consists of a few rare zero fare tickets to a determined destination, valid from January 11 to December 15, 2017. Therefore, it's not an entirely free flight, as taxes and subcharges will still apply.
According to the Qatar Airways website, you can find the Golden Ticket "within the booking results on qatarairways.com during the day the treasure hunt starts in your country." You can participate in the Treasure Hunt on specified dates, depending on your country. Your country has a video containing clues for you to figure out what city the ticket is hidden in. Using the site's search tool, you input different dates until you find the ticket and then complete the booking.