ok so i have played throw mgs4 and i have payed really close atention to the story but i have not heard how ryden became a cyborg and guess ing from the raiden ending im guessing that he was given a new atrifical body but it looked more human cause you can tell cause he has bar codes on his arms and he has thoses slits in his back so he can be conected on that machine that cleans his blood.

im pretty shore its explained in that mgs bible thing on psn so you should go download that because i cant remember what it was lmao xddd

I can't remember the details, but I think he had it done purposely to stand a chance at rescuing Sunny, Olga Gurlokovich's daughter, from the Patriots. This happened in between MGS2/MGS4.

He was tasked with retrieving Big Boss's remains for the Patriots, but he subsequently got caught while doing so. The Patriots held him prisoner and started doing tests on him, specifically exoskeleton. Thus, turning him into what we now know as Cyborg Raiden.

Raiden had the barcodes in MGS2, but the body seems artificial along with his blood. I seem to recall they were going to explain this a little bit more in Rising but that's a totally different game now.

He was in the process of rescuing Sonny from Area 51 with the help of Big Mama, but got caught and turned into a Cyborg.
 
Of course, no one ever thought anything was wrong with building the ultimate soldier, beating him, torturing him, and stealing his body was a bad idea. So then they turn him into a cyborg and shit got reeeeeeeel.

Yes, he was captured and tortured by the Patriots.
 
Edit:  In the cyclical nature of the MGS story, it is similar to what was done to Grey Fox.

@N7: so they actually stole his body and placed his head from the jaw up and his spin was put into a Cyborg body??

I remember something about removing nano machines, since they are all over the body the only way to get rid of them was to turn him into a cyborg and remove his blood. there was also talk of being captured in AREA 51 before MGS4 happened. check the database on PSN to make sure.

@N7: man that is nastey one minute you a normal dude then next thing your head and spine are taken and put on to an artifical body that makes you a badass ninja that dousent feel pain and makes to hit harder and jump higher....whats the down side again???

@N7: man that is nastey one minute you a normal dude then next thing your head and spine are taken and put on to an artifical body that makes you a badass ninja that dousent feel pain and makes to hit harder and jump higher....whats the down side again???

@N7: lol

How do you go from typing Raiden to ryden to raiden?