Re: Crysis just started downloading from Steam....
I don't think it is required for the SP, but after the second patch the MP required it on the first one IIRC.
I am glad the installer didn't crap out and it launched without any problems. @dreamingawake if you are still having issues close steam and try deleting your client regestry.blob file.
It will be recreated when you start steam, but your login info will be lost so make sure you know your pass.