Like everyone else, Atlus and Rock of Ages developer, Ace Team, are doing an April Fool’s day joke…only, they have an actual game to back it up: what looks to be a simplified, 2D top-down version of Rock of Ages.
You can download Pebble of Time (it’s free) by the mysterious “independent developer” on his website (hosted on Google at that). There’s also a lengthy complaint about how developing Pebble of Time turned him blind and few insults thrown Ace Team’s way for good measure.