The Egg-Go-Round (エッグゴーランド,Eggu Gō Rando?) is the boss of Techno Base in Sonic Advance 2. It is a vehicle controlled by Dr. Eggman. The player has to directly attack the cockpit eight (six in easy mode) times in order to destroy the vehicle completely.
Egg-Go-Round is actually an Egg Mobile with four platforms encircling it; two orange and two gray. Each platform has a blue light on it, but these lights can momentarily become red. When a light turns red, something is about to happen to the platform. The orange platforms grow spikes on them, while the gray platforms spin around. At first, the platforms rotate around the Egg Mobile in a clockwise direction, but after four hits, the platforms rotate counter-clockwise.
During the boss fight, the vehicle only moves in the middle of the screen and relies on an endless rail. The player is unable to reach the cockpit, where Dr. Eggman is on. Eggman can shoot electrocuted projectiles from the vehicle's dome towards the player. The only way the player is able to reach the cockpit is jump on to one four platforms and then jump into the cockpit to do damage. However the player has to look at the same time when the orb on either of orange of white platforms start flash blue or red.
The player is only able to hit the cockpit, which has to be precise as the player can got bounced off if he/she hits to the vehicle itself. After four hits, the Egg-Go-Round goes to pinch mode, where platform starts to change their patterns even faster. After another four hits, Egg-Go-Round will be defeated.
The Egg-Go-Round later reappears in XX stage, that is boss rush of the game. During the rematch, it has same patterns from the previous fight and only takes four hits to destroy the vehicle again.