Death Egg Saga
From Sonic Retro
The Death Egg Saga is a collection of four Sonic the Hedgehog games in which Doctor Eggman attempted to turn inhabitants of West Side Island, Angel Island, and other territories into robots to look for the Chaos Emeralds, and assemble the Death Egg, a space station that serves as a base and presumably built to aid Eggman in his plot for world domination.
Also refers to an Archie 3-issue mini-series focusing on the Death Egg.