As part of Sonic Origins, Amy Rose becomes playable in Sonic the Hedgehog, Sonic the Hedgehog 2, Sonic 3 & Knuckles, and Sonic CD.
Headcannon, a developer that assisted Sega with the original Sonic Origins, Sonic Mania and other entries, confirmed it is working on Sonic Origins Plus.
It cited its part in helping make Amy Rose and Knuckles part of certain titles in Sonic Origins Plus.
Among the past Sega projects the company was involved in include the Sonic the Hedgehog and Sonic the Hedgehog 2 re-releases.