This theme is an edited version of the Archie comics version of Sonic. It is predominately darker in tone. This was originally a theme in which Knothole Village's wars were far more horrible and claimed a great deal of lives. This time around it primarily focuses on the anti-verse from the Archie Comics' Sonic continuity, but it still keeps the old theme's more grim dark motif.
Anti-Mobius was a world full of spineless, greedy people. All the different races weren't getting along, and while there were no wars, no one really seemed to get along because everyone seemed to only be out for themselves. Some of the very few people with a mind to change this gathered together and started a movement known as the 'Great Peace'. Not only were there no wars, but eventually nearly all the people of anit-Mobius fell in line and stopped fighting at all. The movement even persisted on after it's figure head, Julius Hedgehog mysteriously disappeared.
Eventually the only thing keeping anti-mobius from being completely stagnant was the acts of Sonic the Hedgehog and his gang, who constantly made fun by terrorizing the more easily frightened citizenry of Mobotropolis. However, this little gang of punks eventually evolved into something far more dangerous and nasty. Over the years Sonic gained power and, after being separated from his gang and disappearing, eventually returned one day as Scourge the hedgehog. He then did just the opposite of his father and suddenly woke the stagnant world of Anti-Mobius with the nightmare of it's first war within memory. Scourge managed to over power (and in many cases kill) anyone who opposed him and then made himself tyrant king of the world.
For nine years he lead the world somewhat unjustly, but had toughened it up a great deal in the process. Due to this, heroes powerful enough to oppose his rule eventually rose from the masses and defeated him entirely, thank fully freeing Anti-Mobius, but leaving it in a lawless state with no sense of order as it had started off, but now with a deal more violence embedded into it.