Sonic Mania Plus is an expanded version of Sonic Mania. On top of the base game that originally released in 2017, it includes a new campaign with two new characters, Mighty and Ray. A retail version was released in July 2018, though the base game can be upgraded to this version by paying for the DLC.
The game includes a new campaign called Encore Mode, up to 4 players in Competition Mode, and two new playable characters; Mighty the Armadillo and Ray the Flying Squirrel.
Mighty's special ability is the Hammer Drop which sends him downward to smash enemies and obstacles below him and knocking hidden items out of trees. Ray's special ability is the Air Glide which leads him travel long distances in the air, similar to Mario's Cape.
In Encore Mode, Sonic is taken back to Angel Island where he finds Mighty and Ray trapped. One of them turns out to be Heavy Magician in disguise and who revives the rest of Hard Boiled Heavies with the Phantom Ruby. Sonic and the other one must defeat them by going through remixed Zones with different color palettes. There is a new party system where the player can swap between the two characters they chose if they are both on the ground. The other characters can be chosen by using monitors to swap with the character on the screen, Instead of lives, the player goes through the 5 usable characters before getting a game over.