When I was hired by Google in 2010, I was sent physical papers to sign and return. I distinctly remember this because Google mailedthe papers to my old address from my first application rather than my 2010 address so I had to drive to my family member's house to get papers on a Friday and send them back by Monday.

I still have email copies of the contracts which they sent in parallel. This includes General Hiring Contract & Salary and a standard NDA with California Section 2870 modification.