Sonic UltraSaturn

A new era is approaching, are you ready? After Knuckles and his new friends defeated Dr. Robotnik and his metal sonic kai, the doctor has disappeared without a trace, peace has reigned for a few months, however it would not last long due to rumors about the Dr. trying to rebuild his metal sonic kai with the pieces he finds on his path, a path that curiously directs him to a very particular point, a wonderful natural spectacle "The Moon of Saturn", a strange satellite that appears every 100 years for 3 days, Why Robotnik Heads there? What plans do you have with "Saturn's Moon" and Metal Sonic Kai? Sadly those questions would not take too long to be resolved, one night a giant hologram with Robotnik's face reported that his plan was underway and that very soon Mobius would cease to exist, crashing Saturn's moon against Mobius in an event that he had called "fat tuesday" Can Sonic, Tails and Knuckles stop Robotnik's plans before it's too late?