A bullethell rhythm game, with plenty of asian girls, j rock and memebon.
It'd sorta play like Ikaruga, cept instead of absorbing color, you absorb rhythm.
You gotta change the color of your ship or something to absorb the rhythm, if you messed up then there would be less rhythm and the music wouldn't be as awesome.
You can customise your ship too, whether it be a giant guitar or a giant slurpee is up to you.
Of course, Beedog and Kimiko would be riding it and the children could fly around the ship like little shields, making you immune to damage (and them of course), for a short time until they return to mother.
It'll be 2D.
And it'll be first released on the Dreamcast and Gamecube, because Dreamcast and because Gamecube d-pad.
Then it'd get so popular, that Cave would port it to iPhone.