Over 10 years since it was first released on the Dreamcast, Bangai-O is back, and boy, are you in for some bullets.
Due out in the (northern) spring, Bangai-O HD is a shiny update of the original, which was first released on the N64 in Japan before later turning up in Europe and North America on the Dreamcast (and spawning a "sequel" of sorts on the DS). It's cute, and bright, and cheery, but don't let that fool you: this game will kick your arse, and when it's done, it'll move onto your thighs and lower back. It's got that much kicking in it.
It's considered one of Treasure's finest works. Since they also did Gunstar Heroes, Radiant Silvergun and Ikaruga, that should give you an idea of how fine that is.