The Egg-Cerberus, also spelled as Egg Cerberus, is the first boss faced by both Sonic and Shadow in Sonic the Hedgehog (2006). Sonic faces it before Dusty Desert and Shadow faces it after White Acropolis.
It is a giant dog-like robot, although its appearances in both Sonic and Shadow's stories lead to speculation on whether or not there is one or two of them. (Since the one in Shadow's battle seems rusted.)
When the player begin the battle, the player has absolutely zero Rings. Race around the arena, picking up the gilded treasures for safety. Look for some Ring Capsules along the outer walls of the arena. After the player has picked up some Rings, pursue Egg Cerberus. The monster wildly bucks and stomps around the arena, but eventually slows down its gears long enough for you to hitch a ride on its tail. When the beast lowers its tail to the ground, jump on it and grind to Egg Cerberus’s head. If the monster starts moving again while the player is grinding, the player will be kicked loose. When the player grabs the neon pole, the player controls Egg Cerberus for just a few moments. The machine freaks out and start bucking like a wild horse, but the player can still steer it. Smashing into walls causes a little damage to the monster, but to maximize the player effectiveness, steer Egg Cerberus into the two statues on opposite sides of the arena. A direct hit drains half of the beast’s health. After smashing into a wall, Egg Cerberus shakes you lose, sending the player into the air. After taking its health down halfway after the ﬁrst big smash, the Egg Cerberus leaps out of the arena and stands on a circular ledge that directly overlooks where Sonic stands. The monster jumps high into the air; when it comes down, the shock wave from the impact rattles the entire arena. Keep a lookout for the Egg Cerberus’s shadow as it descends, because the player need to get some distance from it. If the caught in the shock wave, the player lose his Rings. Continue avoiding the Egg Cerberus’ massive attacks and take control of the monster whenever it lowers its tail. If the player strike both statues, the Egg Cerberus falls otherwise, the player need to drive the monster into the walls four times in order to bring the beast to its knees.
As soon as the boss battle starts, the Egg Cerberus roars into action and gallops around the arena, smashing into guard towers. The monster goes on a brief rampage before it’s forced to slow down and recharge its energy. When the monster is stopped, the player can rush up and jump on its tail. The Egg Cerberus does not stand still for Shadow as long as it does for Sonic. Stick close to the brute so the player can capitalize on every chance to grind its tail and backbone and leap up to its head to grab the reins. If the player start the grind too late, the monster will shake the player off as it jolts into motion. Steering the Egg Cerberus isn’t easy. If the player doesn’t chart a direct course through the arena’s center, the monster can curve away from the walls and avoid a collision. There are no spots in the arena walls that cause extra damage, the player just have to plow into the metal walls four times to disable the Cerberus’s circuitry. After the player hit a wall, the monster kicks the player loose, sending you high into the air. There are lots of Rings in the arena you can pick up for protection, but most are guarded by Eggman’s robots. The white robots only have machine guns, but the red robots employ missile launchers. Use the Chaos Spear to shock the robots into submission, then use the Homing Attack to smash them. Keep tabs on the Egg Cerberus while attacking the robots, though if the player isn't careful, the titan runs the player over when the player is not looking. Watch out for when the Egg Cerberus leaps out of the arena and stands on the ledge surrounding the fortress interior. The monster is charging a jump. It will launch itself into the air and come crashing down on the ground, sending out a terrible shock wave that shakes loose all of the player Rings if the player is caught in the middle of it. When the player see the Egg Cerberus leap into the air, start running and get ready to jump just as the player see its front paws hit the ice. Chase the Egg Cerberus around the arena so that the player can jump on its tail the moment it stops moving. If the beast turns and faces the player, watch out for a very specific movement. The lone eye will ﬁxate on the player position and the head will dip low. When that happens, the Egg Cerberus is about to rear up on its back legs and slam its front paws onto the ice, sending out a small shock wave. As soon as the player see the monster eyeing you, make yourself scarce and keep jumping to avoid the shock wave. After defeating the Egg Cerberus, Shadow and Rouge return to Soleanna’s capitol city to further investigate Dr. Eggman’s activities. From town, Shadow and Rouge must strike out to Kingdom Valley, the crumbling site of the royal residences. Once Shadow reaches Kingdom Valley, he will discover how his fate intertwines with Sonic The Hedgehog’s as he comes face to face with his greatest nemesis.
- The Egg-Cerberus is named after a dog in Greek mythology, Cerberus, who was a three-headed, fire-breathing, demonic dog who guarded the entrance to Hades' Underworld. However, the Egg-Cerberus has only one head, unlike the Cerberus in mythology.
- During Sonic's battle, the Egg-Cerberus is referred to as Dr. Eggman's "pet" and in during Shadow's battle, it is referred to as his "guard dog".