Tiara Concerto, a game focused around musical gameplay in floating castles in the sky. And with all joking aside, it seems like a pretty interesting concept at face value, although it's a bit difficult to divine how well it will play out over time.
According to the game's backstory, the game takes place 800 years in the past, with humanity on the brink of eradication due to the ambiguous sinning of mankind. The Seven Wise Men helped preserve civilization in floating palaces, developing the art known as "tuning" to allow musical melodies to be used as weapons. While the localization appears to be a bit scattered, the trailer just past the cut certainly promises some interesting visuals if nothing else. You can also look at the official Facebook page, which features a series of comics translated to English to help introduce the game's concepts and play style.