Sonic Mania Launches for PC, is Accidentally Online-Only

Steam users are unable to play the game in offline mode, despite Sega's insistence that the game is intended to be playable offline.
Denuvo's copy-protection system seems to be the problem.

Sonic Mania Plus, Sonic Wiki Zone

Sonic Mania Plus Review for Nintendo Switch: - GameFAQs

Sonic Mania (Review)

Sonic Mania - The Cutting Room Floor

Beyond Good & Evil 20th Anniversary Edition Accidentally Leaked by Microsoft

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Sonic Mania Plus - Official Trailer : r/Games

Game's Mania

Sonic Superstars, Sonic Wiki Zone

Sonic Mania Launches for PC, is Accidentally Online-Only

Sonic Mania - Opening Animation : r/Games

The Switch Accounted For 52% Of Sonic Mania Plus' Launch Week Sales

Sonic Mania's Denuvo has been cracked in just eight days since launch : r/Games