Hard Boiled Heavies

The Hard-Boiled Heavies (ハードボイルドヘビーズ) are a group that appears in Sonic Mania. They are a team of elite Egg-Robos created by Dr. Eggman. They work in private, but appear in front of Sonic many times over the course of his adventure. However, this evil group eventually evolves into something even Eggman could not predict.

Concept and creation
Christian Whitehead came up with the Hard-Boiled Heavies after imagining Eggman entering a state of depression after Sonic the Hedgehog 3 & Knuckles; instead of going after Sonic, he would merely lounge at home in his pajamas and that the abandoned Egg Robos would go "a little mad." After thinking about this concept, the term came into being.

History
Based on the Egg-Robo, the Hard-Boiled Heavies meant to handle Dr. Eggman's most important tasks. Upon detecting a highly powerful energy source, the Hard-Boiled Heavies were sent to investigate it by Eggman.

Gameplay
In the gameplay of Sonic Mania, the Hard-Boiled Heavies fill the roles of bosses in each Zone's Act 2 (with the exception of the Heavy Gunner, which is in Act 1) each one of them having their own unique set of abilities.