Known issueFixUpdated · 3 replies on Steam
Phantom Blade Zero: RED Screen Stuck (Workarounds)
Short answer
Suggested fix (unconfirmed): Uninstall any installed game mods, as they are falsely triggering the anti-piracy screen. Then, verify the game files through Steam to restore original files.
The problem
I have a RED home screen with the message that my game is a pirated version... I bought it directly on steam... So I cannot launch the game since the update.. please help
Did this work for you?
Source: original Steam Community discussion. Quotes are shortened; all credit goes to the posters.