The spin jump is the primary offensive maneuver of Sonic the Hedgehog
and friends in the Sonic
video game universe. Unlike hop-n-bopper heros such as Mario
or Diddy Kong
who must make contact with their feet in order to defeat a baddie, the spin jump enables the character performing it to roll up into a ball, causing most badniks that come into contact with any portion of him/her to be defeated. The theory behind this behavior is that when Sonic
performs the move he rolls up into a ball, causing his spine
s to be exposed. These spines combined with the intertia and momentum of the jump is what causes the enemies to take damage. Enemies that utilize spikes, flame, and extreme cold counteract the spin jump and cause damage to the character performing it.
The move first appeared in the original Sonic the Hedgehog game. When Tails was introduced in Sonic the Hedgehog 2 he was also able to pull off the move, although why it is effective in damaging badniks is unexplained as Tails has no spines to cause damage with. When Knuckles was introduced as a playable character in Sonic and Knuckles he was also able to perform the spin jump, setting the precedent that the move is the standard weapon of playable characters in the Sonic universe including the aforementioned Sonic, Tails, and Knuckles as well as Cream the Rabbit (from Sonic Advance 2), Shadow the Hedgehog and Rouge the Bat (both from Sonic Adventure 2 and Sonic Adventure 2 Battle). Major characters who are unable to perform the spin jump include Amy Rose (who instead is armed with a large hammer) and Dr. Robotnik (who does battle from his personal battle mech).