The game shows tiny clips from the new TV ad – due to be released soon – with clues hidden in the snippets. Those clues, entered into Google, bring up a number of websites all based around the ad, each with further clues.
Players can win the chance to be the first to see the new ad, a solid gold domino worth £800, and other Guinness merchandise. The campaign is part of Guinness's Good Things Come To Those Who Wait campaign.
Marketing manager Paul Cornell said: "It's no longer good enough to do an ad on TV. We want people to chat about it and generate online communities talking about the different clues and how they can solve them, and to chat about the Guinness ad and the Guinness experience.
"At the moment 5-8,000 people are playing the game at any one time."
To play the game visit guinness.com.