Lose after lose Doctor "Eggman" Robotnik doesn't take anymore to have his schemes ruined by Sonic the Hedgehog. But this time something was oddly different. The Chaos Emeralds were not scatered by South Island, but... The Koopa Empire?

"That gives me an idea" muttered Eggman to himself, smiling.

Of course! If he can not defeat Sonic and his friends maybe he could be able to fight Bowser and his minions instead. If Eggman could roboticize the mighty Koopa King and all his army taking over the whole world would be piece of cake.

Excited about his new plan, Eggman begins to mount his new EggMobile weapon, the EggWalker, a super gadget capable of shooting plasma, jet propulsing and even water diving. Eggman giggles predicting his triumph...

Can Eggman and his new toy defeat the great army of the Koopas?