Basically, it becomes a phenomenom.
The first Just Dance was launched in December 2009. Despite the skepticism around its dance-centric proposal (and some bad reviews), it slowly climbed its way to the top of the charts, thanks to word-of-mouth.
However, what sent its brand awareness through the roof happened in December 2011, when Barack Obama was photographed buying a copy of Just Dance 3 for the Wii, as a Christmas gift for his daughters. That single event helped catapult mainstream recognition, as Xavier Poix, Managing Director at Ubisoft Paris, said in an interview with IGN:
My first thought was that our PR in the U.S. must be really good, but no, I was thinking: now we’re universal. The image that we wanted to convey with the game, the spirit of it, really worked. The president, in front of 80 cameras, can think, ‘I’m not making a mistake in showing that I love this game.’ It is so simple and positive that nobody could object. We’re very proud of that.
Now, 4 years after its first launch and 2 years after the Obama photo, Just Dance is one of the most successful series in the world, having sold around 50 million units (more than Pac-Man or Tomb Raider, to name a few).