Each band in Mashups represents a different genre of music: country, marching band, funk, etc. Songs are played as duels between two bands, with each band playing the licensed soundtrack in their own style. The style of the audio track alternates, with the winning group's style coming through more clearly. The game is controlled by moving the Wii remote left, right, down, and forward to match onscreen cues.
The cleverest thing about this game, we think, is how it turns a problem into a positive. Guitar Hero dealt with the issue of not having access to original recordings of licensed music by recording soundalikes. Planet Moon realized with Band Mashups that a cover doesn't have to sound like the original, and built a game around it. We are actually looking forward to hearing all the cover songs. Symphonic "Spoonman"? Latin "Blitzkrieg Bop"? Yes, please. The full soundtrack includes other weird and wonderful choices like Tenacious D's "Master Exploder" and "Man of Constant Sorrow" from O Brother Where Art Thou. More screens and even video are available at the IGN link.