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

Sonic Frontiers - Wikipedia

Sonic Mania Delayed, Project Sonic 2017 Receives Official Name

Sonic The Hedgehog: 25 years of a video game icon Part 2 – Blueknight V2.0

Sonic Fans Club

Sonic Fans Club

Sonic Fans Club

SXSW Sonic panel: News announcements roundup - The Independent Video Game Community

Sonic 2017's official title is Sonic Forces, Sonic Mania delayed to summer

Sonic Mania (for PC) Review

Sonic Mania is indeed out this August, and here's a new trailer