This guide applies to Sonic Mania 1.05.0713 and below, and does not apply anymore unless you downgrade to an earlier version, i.e. using a depot downgrade tool, i.e. for mods or to play the pre-Plus version.

Game begins to start, displays the logos, then crashes right before the Sonic Mania title screen.

Game unlock key may be corrupted, or a system update changes the system profile in a manner that the Anti-Tamper doesn't correctly detect. This causes certain parts of the game to decrypt incorrectly, causing a crash.

Make sure your game is up to date; as of version 1.06 Sega has removed the Denuvo Anti-Tamper wrapper. If you decided to use an old build, i.e. for mods, follow the instructions below if you have the crash.

You will need to delete the Denuvo activation files stored in your Steam userdata folder. Follow these steps:

• Open your Steam installation folder. Default is C:\Program Files (x86)\Steam for 64-bit systems or C:\Program Files\Steam for 32-bit systems.
  
• Open userdata, then the numeric folder that matches your account, then folder 584400.
  
• Select the 1 or more files that consist of numbers and no file extension, and delete them.
  
• Ensure your Steam client is in full online mode and your Internet connection is active.
  
• Start Sonic Mania. The game should start and run correctly.
  
• Contact Sega Support even if your game launches and plays, so they can be aware of this issue. You can find the Sega Support contact for your country at http://www.sega.com/support