The boss of Green Hill Zone is the first boss fought in Sonic Blast. It is an Egg Mobile equipped with a boomerang-like device.
This boss is a relatively simple one. Dr. Eggman will attack Sonic or Knuckles with the boomerang. He emerges from the right and will fire the boomerang twice into the bottom left hand corner before moving to the other side of the screen to attack the right hand side. Unlike previous outings, Eggman can only be damaged by hitting the windscreen of the Egg Mobile. Defeating the boss will allow Sonic and Knuckles to travel to Yellow Desert Zone.