From G4TV:

Harmonix’s Rock Band franchise has been laying low since the release of Rock Band 3, with yearly releases of high-profile plastic-instrument orgies a relic of gaming days gone by. But Rock Band Blitz, an upcoming downloadable title, points to a bright, but scaled down future for the series.

Blitz is a downloadable music game along the lines of Amplitude or Frequency that aims to take the rhythms and melodies from your favorite music and transform them into gaming elements in a flat-out action arcade game. It’s part-beat matching, part pinball, and judging from my playtime, all fast-paced, arcadey fun, especially if you’re a music fan. If you hate music, maybe do something else.

Gone are the performance or simulation elements from past Rock Band games. Instead, Rock Band Blitz aims straight for the brightly lit guts of old schoolish arcade action. The game leverages the music library you’ve built up over the years purchasing DLC for Rock Band, Rock Band 2, and RB 3 through the Rock Band Network and lets you use them in a new way.