Sonic Mania is a game made for fans, by fans, so it’s only appropriate that the developers paid tribute to one of the most beloved members of the series’ hacking community.
Cody “Polygon Jim” Lawrence was a prominent member of the Sonic hacking community who died in a car crash in 2013, when he was 21 years old. Four years later, Sonic Mania developers honored him by including one of his most popular creations in the game as a part of a boss fight.
Polygon Jim’s creation, Motobug the Badnik in Sonic the Hedgehog, replaced Sonic with one of the game’s first enemies, the motobug, as the main character. The motobug protagonist is mostly the same as the normal enemy, but can jump by extending its wheel.
For the tribute in Sonic Mania, the Heavy Rider boss fight in Lava Reef Zone features a robot with a flail riding a jumping motobug named Jimmy.
Sonic Mania was created by multiple fans of the series who made popular hacks of the games as well as developers of some of the earliest Sonic games. The reference to Polygon Jim is a heartfelt tribute to one of their peers and a really nice way to honor a friend of the community.