At the risk of sounding horribly behind-the-times and stating the obvious, here's the gist of "Just Dance": There are bunch of routines to real songs (mostly original tracks, with some quality covers), and each is led by a CGI dancer that seems to have been motion-captured from a real dancer. The CGI dancers wear amusing costumes appropriate to the songs. It's a surprisingly decent workout, as long as you don't take (long) breaks. The menu ranks each dance routine by difficulty and intensity, so it's possible to engineer an hour-long sweat-fest simply by choosing the harder selections -- such as this aerobics-inspired number:
Or this '90s jam:
Fun, right?