3 years after Shadow defeats Black Doom, he's having nightmares about his past, one of his nightmares is Shadow helping a young girl (Maria) while escaping from Space Colony ARK, in this nightmare, Maria has been killed by Black Doom. After woken up, Shadow has been captured my G.U.N forces, and the G.U.N forces make a deal - You help us and you are free or you don't help us and die in this jail.
Stages
Stage 1 : G.U.N Help (Hero) / Waiting a Miracle (Neutral) /Prison Break (Dark)Rocky Mountain Escape in PSP Go.
Shadow is the main character , he can choice three paths , Hero , Neutral and Dark. Shadow main objective is defeat Black Doom and discover her past (Hero) / Escape from Prision (Neutral) / Defeat G.U.N forces and discover her past. (Dark)
He return in this game with new two forms : Super Black Doom and Ultra Black Doom , Super Black Doom is a hero-only boss and Ultra Black Doom is the Final Story boss , he was nothing to do with story , this two forms is a dream.
The game has mixed reviews , the average score is 72/100 , because a lack of graphics and also the Neutral stages are lamest to no have action. The Hero and Dark mode are cool but the old graphics changes everything , the storyline is confuse because Black Doom is a dream? , but the action of Hero and Dark mode are good and the controls are better.
The Good Future , hero stage , is based in Sonic CD , because levels in Sonic CD have a Good Future
The Stage 10 of Dark Story , I will survive , Is based of a music with the same name.
This is the first Sonic game for a PSP who don't have Sonic as playable character , he's appears in Final Stage of Dark Mode , but , It's not Sonic himself , is giant robot.