A lot of content in MGS2, you can see the original plan
on this PDF
Some tidbits:
- The Ninja on the Plant Chapter was supposed to be a female robot that would change her voice & personality based on whoever was closer (Snake->Meryl, Otacon->Sniper Wolf)
- The player would have been given the choice of saving either Emma or the President, and Snake would rescue the remaining one.
- Johnny Sasaki was intented to be killed after making contact with Raiden and giving him a keycard.
- The original Codec staff of Raiden where intented to be more people (everyone being an AI), with similar roles of the MGS1 crew. Most of them were references to the New York book series "City of Glass", and later where mixed with the main ones.