https://www.gamespot.com/articles/sonic-mania-pc-versions-unexpected-drm-angers-play/1100-6452993/

Following a last-minute delay, this week's release of Sonic Mania on PC brought with it some unpleasant news when players discovered it uses the much-maligned Denuvo DRM. Worse yet, the game could not be played offline, although that particular grievance has since been resolved by Sega.