If you failed to guess it at this point the mystery theme is Hedgehog Havok! based on the Archie Sonic issues 195 to 196 in which Sonic and Amy Travel to an Anti-Universe to find a way to get rid of Scourge (This universe's counterpart of Sonic who hijacked their HQ) Sonic and Amy look for allies to which they learn about a girl who really REALLY hates Scourge, the Anti-Amy Aka "Rosy The Rascal" however when they meet her they find out that she is quite insane due to using a magical ring to turn older (Amy did the same thing in the comics but didn't have the same side effects), Back in Sonic's Universe, Scourge is betrayed by his teammates and Sonic makes a de-turn back into his own Universe for a second until both Sonic and Scourge are thrown in to the Anti-Universe with the portal closed, now Scourge and Sonic have to deal with the Hedgehog Smashing Rosy who wants nothing more then to see them splat under her hammer…

AT THE SAME TIME Silver the Hedgehog arrives in the past and is looking for Sonic who he believes is the cause of the future's demise and meets with Rob'o The Hedge (Amy's Cousin who resembles Sonic and Robin Hood) Rob'o agrees to help Silver find Sonic (not knowing Silver's true intention)

so while Sonic, Scourge, Amy and Rosy are fighting out of nowhere Shadow appears in a flash and soon after Metal Sonic appears in a flash hunting for Sonic and to top it all off Silver and Rob'o Arrive via Warp Ring and we are greeted with an all out Hedgehog Battle royale! Sorry thats a lot more then I usually put in my descriptions, I'd recommend you find a copy of the issue to read, it's one of my favorite story arcs from the comic and I always wanted to do renders based on it!