Favorite unused idea / cut content?

[MGWSpike]

There were various proposed ideas that never became a reality during the development of MGS2. Or content that ended up being cut either because it was boring, didn't make sense or because of self-censorship following the 9/11 attacks. 

They're gathered in this article. Here's the info as a partial list below:

Spoiler:

Unused ideas
- A Penguin suit giving Snake infinite O².
- A cell-shaded look based on Yoji Shinkawa's artwork, with Snake wearing all of his weapons.
- Raiden conceived as a creepy character licking bird poop and moving a bit like Spider-Man (partly reused for The Fear in MGS3)
- Raiden conceived as a cyborg with a triangulat chest panel.
- The A.I. Colonel would be a different character, Daniel Quinn, instead of mimicking Campbell.
- Additional A.I. support team members: Maxine Work (based on Mei Ling), Doctor William Wilson (based on Master Miller)
- Peter Stillman would have been an alternate universe version of Ed Brown from Policenauts.
- Dead Cell would have been called Black Cell and its members would wear sunglasses (Dead Cell / Black Cell is based on the real-life Red Cell).
- Additional bosses: Chinaman (parts of his powers/gameplay were given to Vamp) and Old Boy, a 100-year-old mentor of Big Boss (recycled as The End and The Boss in MGS3)
- Fortune playing the saxophone during cutscenes (for example when she exterminates SEAL Team 10).
- Vamp as a female character and being in an actual relationship with Fortune (his dead lover's daughter).
- Ocelot with a cybernetic arm (done in MGS4).
- Olga with a more feminine design (recycled for Olga Kalinina in the video game Left Alive).
- Pliskin being as less able blond bearded man in his 50s speaking with Liquid's voice.
- The church incident where Vamp was wounded and the one where Peter Stillman couldn't defuse a bomb were one and the same (in the final game, the dates don't add up).
- Split screen gameplay/cutscene sections (achieved in MGS4).
- If Raiden caught on fire during Fortune's boss "fight" and the player didn't react, his hair would burn and he would end up bald. He could obtain various wearable wigs afterwards, but they would fall if he did cartwheels and such (hence the optional Codec conversation where Raiden tells E.E. that's his real hair as well as the unlockable wigs).
- The Female Ninja wearing an aquatic version of the exoskeleton and changing her voice according to the character she's speaking to (talking as Sniper Wolf to Otacon, as Meryl to Snake, ...). Her true identity would remain unknown but she's actually an A.I. construct created by the Patriots.
- Rosemary being a hostage Raiden never actually meets and that he can't save, so he's left wondering if she actually existed.
- Rosemary being blonde (she mentions changing her hair to suit Raiden's taste in the released game).
- Emma being on her period and making a period joke after being fatally wounded by Vamp.
- A boat chase before the swordfight in New York.
- A 2-player versus mode.
- An aquarium with marine life / a virtual exploration of the ocean
- Snake revealed as a spy working for China (recycled for EVA in MGS3).

Cut content
- The FAMAS and an underwater pistol in the Tanker.
- Escaping the flooding waters in the sinking Tanker.
- Vamp criticizing the US population and being glad to use the bomb against them.
- Raiden considering the POTUS to be potentially a terrorist for giving the nuclear codes to the Sons of Liberty.
- Liquid willingly sending the Arsenal Gear straight into New York to perpetrate a full-scale disaster.
- A long cutscene showing Arsenal Gear destroying the NYC buildings and moving the Statue of Liberty.
- The US flag falling on Solidus's broken body.
- The coda with Karen Hojo reporting on the Statue of Liberty.

Is there any concept you regret not making it into the final game? Or do you think they wouldn't have improved the game?

Personally, I would have liked to see the original Female Ninja concept.