Ok, does anyone remember the cinematic scene in Halo 2 where the MC and the Arbiter were being held by Gravemind? Ok, if so then do you also remember the Phophet of Regret and the Red Oracle....otherwise called 2401 Penitent Tangent? If getting the acheivement in Marathon says:
Hats off to 819
The secret of 2401 lies within.
Then did anyone do some research into that? From what you said, unlocking all of the terminals in that game gets you that acheivment. Think about it...2401 speaks of activating all of the installations (terminals) and that if one is destroyed, the rest remain on standby for remote activation which is what the Prophet of Truth was on his way to do at the end of the game. I'm assuming that '819' is some sort of significant number. Maybe since there is Spartan 117 there is a Spartan 819? Maybe an Oracle 819? Either way whatever '819' is directly linked to in the Halo Universe gives the plotline to Halo 3.
Looking into it a bit...and i don't mean a bit...that would be an understatement. I came across a few things that could POSSIBLY make sense but take note to the fact that I have not read any of the Halo novels but have glanced over them a few times. During First Strike Dr. Halsey hijacks a shuttle for her own private mission to the planet Onyx. There, she assists in deciphering the surrounding Forerunner ruins on the planet and leads the surviving humans within a Dyson Sphere contained within the spatially compressed core of the planet, in actuality a "shield-world" construct left unused by the Forerunners. Also, from what I read, she also led 3 other Spartans into the Dyson Sphere. Also contained in the Dyson Sphere is a Dyson ring. Larry Niven (the write of a book called Ringworld) himself thinks of the Ringworld as "an intermediate step between Dyson spheres and planets." A Dyson Sphere from what I understand is almost like a protective bubble of the Dyson ring. I probably don't have all of this put together correctly but i'm thinking is that Dr. Hasley and MC will once again meet, as well as the other 3 Spartans. I don't know. I still havent found any direct connection to 819 but it might be some protocol or what not. This is all rather frustrating. Some please respond with some contstructive criticism.