Music games such as Guitar Hero and Rock Band once lit up the charts of video game sales. But then they plunged into an abyss as gamers got tired of the stale content. Fortunately for Ubisoft, gamers only tired of the games that were duds, not all music games.

Today, Ubisoft is announcing that it has sold more than 5 million copies of Just Dance 2 for the Wii. That’s a huge success, making it one of the top three game franchises of any kind for 2010. And it comes off an earlier announcement that Ubisoft’s Michael Jackson The Experience game for the Wii sold 2 million copies in just six weeks. From the point of view of French publisher Ubisoft, music games are back, said Adam Novickas, director of marketing at Ubisoft, in an interview.

It shows that game genres don’t die. They go through cycles of innovation where original titles delight users, and then periods of stagnation when users get frustrated with the lack of variety.

Just Dance 2 was released in October. Combined with its predecessor Just Dance and Just Dance Kids, the franchise has sold more than 10 million units since its debut in November 2009. It’s also the third-bestselling third-party Wii title in the console’s history. The Michael Jackson dance game came out on Nov. 23 and its Xbox 360 Kinect and Sony PlayStation Move versions will come out this spring.

Overall, Just Dance 2 generated an estimated $200 million in retail sales, while Michael Jackson The Experience generated sales of $80 million. The numbers are based on sales to end customers.

The solid performance of Ubisoft’s titles contrasts with weakness in the Rock Band and Guitar Hero franchises. Viacom was so sour on Rock Band that it allowed developer Harmonix to buy the property back for a song. Going into the holidays, music games were down 50 percent from year ago sales, according to Wedbush Morgan Securities analyst Michael Pachter.

In Just Dance 2, up to four players can try to mirror the dance choreography featured on the game screen. The game has more than 40 tracks, with more available for downloading such as Katy Perry’s hit Firework.