Board Thread:General Discussion/@comment-25221943-20170321020842/@comment-679780-20170321052606

My old theory was that Modern Eggman went back in time to assist Classic Eggman, thus replacing the classic era with Sonic Mania and Classic Sonic in Forces is from Mania.

But chances are Sonic Mania is a stand-alone game. Eggman may have gone back in time and gone all Aku on Classic Sonic.