Original file: http://steamcommunity.com/app/17300/discussions/0/864945401070748061/
This is the 64-bit binaries for Crysis. It allows the game to be run as a native 64-bit application, providing various benefits and enhancements.
Extract the contents of the download to the Crysis installation folder.
Run the crysis.exe file in the newly added folder (Bin64) to play the game.
(Optional) Create a shortcut of the EXE for the Desktop for easier access.
For the Steam version, there is a way to make the Steam client launch the 64-bit version by default. In the Crysis installation folder, rename the Bin32 folder to Bin32.bak and rename the Bin64 folder to Bin32.