Theory mentioned by Retiredmickeymouse! Yaaayy! You know the game "sonic the hedgehog", right? Even if you aren't a big fan or know what it is, you've gotta admit, its pretty successful. But u know what? TINFOIL HATS!!! There's a theory going around that our beloved blue hedgehog and his friend don't exist in their actual dimension. You see, how do people go faster that the speed of sound? By machine, right? Well, by the human-animal race, running by itself isn't very fast. The theory states that Eggman was just a parent/guardian playing along, while the kids, the characters ( sonic, tails, etc. ), pretended to be humanoid teenagers with special abilitys. Their guardian is just probably a mechanic or inventor, not some crazed robot-making weirdo.
