Since shortly after the Wii Remote first brought motion control to the masses, we've known that over-enthusiastic use (and slippery hands) can lead to controllers (and other things) getting broken. So what happens when Kinect's 3D camera turns your entire body into the controller? Well, not surprisingly, it turns out you're the one that could get broken.
"Versus mode was a bit too dangerous," Fighters Uncaged producer Luc Verdier said when asked about a competitive mode for his newly announced Kinect-enabled fighting game. "It's possible to do, but people just end up hitting each other." Thus, the game's only multiplayer mode is a cooperative battle, where two players work together against the artificial intelligence.
Of course, people don't usually end up killing one another while playing games like Just Dance, even if four players are moving about in an enclosed space. But Verdier said motion-controlled games where multiple players are synchronized are safer than games where the players can just "do whatever." We'd also hazard to guess that dancing players just tend to be less intentionally violent than fighting game players, especially when those fighting game players are actively playing.