Here is the secret ending you get if you beat halo 3 on legendary [url]http://www.youtube.com/watch?v=Yygn_vlH5a4[/url] If you watch it the whole way through you can see that MC lives.
Here is a secret movie never released (it was leaked) [url]http://www.youtube.com/watch?v=RuzPRV4L95s[/url] Creepy huh? Here is a quote from that page "The strange sounds in the Halo 3 terminals are actualy from a Rogue Forunner AI (Artificial Intelligence) known as "Mentinent Bias". If you look at all the strange sentences in the red paragraphs, they say things like: I "AM MENDICANT BIAS THIS IS WHAT I HAVE DONE //FRAGMENT 7/7 [RECORED VERBATIM AND INTERPRETED POST-CATACLYSM]" The reason for this is that he was corrupted by Gravemind, but now he wants to help the Master chief. He cuts the portal at the end of the game to get MC's help and that means it ties in with marathon"
In the halo 3 campaign u can find hidden terminals around some off the maps they are left over fragments from the forerunners and they tell of the flood and many other intresting stuff the last one u can find tells a a leftover forerunner dyeing after destroying the flood.
