Sonic Has Just Found Out That Every Eggman From Every. Single. Universe Have Teamed Up To Take Down The Entire Multiverse, So Now, Sonic Must Travel Across The Sonic Multiverse, Gathering Every Sonic From Every Universe To Take Down The Eggmen.

Sonic And Tails Are In The "In Between". A Place Outside Of Time And Space, Shrouded All In Different Portals To All The Multiverse. Simply Accessed By Tails' Portal Gun

Tails: So, Where Are We Gonna Go First?