Sonic 2017's Official Title is Sonic Forces, Sonic Mania Delayed to Summer

SEGA announced a pair of updates regarding the two Sonic the Hedgehog games the publisher has in development.
The first gameplay of modern Sonic in Sonic Forces is coming soon.

Sonic Fans Club

Sega came up with a way to get fans excited about Sonic the Hedgehog again

Sonic Mania Delayed, Project Sonic 2017 Receives Official Name

Sonic Mania Preview - Knuckles Returns To Flying Battery Zone In Newest Sonic Mania Trailer - Game Informer

Sonic the Hedgehog (1991 video game) - Wikipedia

Sonic Mania' delayed, 'Project Sonic 2017' is called 'Sonic Forces

SXSW 2017: Project Sonic 2017 is Sonic Forces / Sonic Mania delayed to Summer 2017 – Blueknight V2.0

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Sonic Mania delayed

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Sonic Mania Plus, Sonic Wiki Zone