Retro City Rampage became a huge indie hit and parodied, amongst others, Grand Theft Auto. It achieved both critical acclaim and commercial success, so it was only a matter of when the sequel would be released rather than if. Therefore it wasn't too surprising when Shakedown Hawaii was announced a couple of years ago, but since then no release date has been revealed.
But now it seems like the launch perhaps isn't to far away, as Vblank Entertainment has launched Steam page for the game where it is stated that the game launches sometime this year. Shakedown Hawaii takes place 30 years after the events of the first game and the formats announced are PC, Nintendo 3DS, PS4, PS Vita, and Switch.