If you own the Crysis 3 Remastered version (released 2021), this patch does not apply to you. This guide is for the original 2013 release.
The registry keys for Crysis 3 are missing (common if you moved the folder or upgraded Windows). Fix: crysis 3 patch 1.3 download
Improved internal security measures to combat hacking in multiplayer. If you own the Crysis 3 Remastered version