Seven

"Some of you may be wondering - "What's up with this unhealthy obsession with the number 7?" This page offers some insights."

- Luke Smith, linking to this very page

"Cause that's the best number. It's like rock. Nothing beats rock or 7."

- Michael Wu

Bungie Studios has long enjoyed using the number Seven (7) in its games in many prominent ways. Ensemble Studios and authors also have certain obvious seven references in their works about Halo. While almost anything can be made into a reference to something with effort or construed accidentally through pareidolia, the following attempts to list the intentional references Bungie placed into Halo for the fans to find. As such, not all of these references may be fully accurate, and many of them may be proven to be false at any time.

117
117 is Master Chief's SPARTAN tag number, but there is more than meets the eye when it comes to this number, including many religious and historical references. 1x1x7=7
 * 'John' is four letters long, and his service tag (117) is a three digit number. $$4 + 3 = 7$$

The Halo PC trail has a total of 117 files/folders

Biblical Reference

 * John-117 is believed by many fans to be a reference to New Testament of the Christian Bible.


 * In the year 117, the 7th Pope of the Catholic Church was named, Sixtus I,as well as John 1 becoming 7th bishop of Jerusalem.


 * The Gospel of John speaks of the 7 miracles of Jesus, the last one, John claims, culminating in his death.


 * Bungie Studios is known to have placed many biblical references in their earlier Marathon video game series, and many other such references have been found in the Halo series.


 * Here are passages from the Book of Revelation (more formally known as The Revelation of St. John the Divine). Revelation in Greek is called "The Apocalypse", a title possibly shortened from "The Apocalypse of John."


 * "And when I saw him, I fell at his feet as dead. And he laid his right hand upon me, saying unto me, Fear not; I am the first and the last: I am he that liveth, and was dead; and, behold, I am alive for evermore, Amen; and have the keys of hell and of death."
 * Book of Revelation, KJV. Chapter 1 - verses 17 and 18.


 * "And when they shall have finished their testimony, the beast that ascended out of the pit shall make war against them, and shall overcome them, and kill them."
 * Revelation. 11:7


 * There are also references in one other book of the Bible. 1 John houses these:


 * "But if we walk in the light as He is in the light, we have fellowship with one another, and the blood of Jesus Christ cleanses us from all sin."
 * 1 John 1:7 (1 John 1: 7)
 * "And the world is passing away, and the lust of it; but he who does the will of God abides forever."
 * - 1 John 2: 1 7


 * And here are passages from the Gospel of John. These are thought less likely to be references:


 * "Then after that saith he to his disciples, Let us go into Judea again."
 * Gospel of John, 11:7


 * "For the law was given by Moses, [but] grace and truth came by Jesus Christ."
 * Gospel of John, 1:17
 * "There came a man who was sent from God; his name was John. He came as a witness to testify concerning that light, so that through him all men might believe."
 * Gospel of John, 1:1-7
 * (Out of all of these, perhaps the most likely to be a reference to Spartan-117 would be the last verse.)


 * Halo 3's plot also resembles the story of Noah's Ark. Because the Forerunners kept a few of every sentient species in the galaxy in the Ark because the parasitic life-forms known as the Flood were coming, much like in the bible story of Noah's Ark. The flood was coming and Noah put two of every animal in the Ark to save them from the water flood, much like the Forerunners did before they activated the Halos to keep the other lesser sentient species from extinction.

Site 117
Alternatively, others believe the number to be a reference to "Site 117", an archaeological site containing the first evidence of a human battle. The site is near Jebel Sahaba, Nubia and dates from between 12,000-10,000 BC. The site contains 59 human remains of men, women and children who were clearly killed with primitive hunting implements.

117 and 7
It is conjectured that the numbering system for Halo installations' Monitors is, where $$n$$ is the number of their installation, $$7^{n-1}$$. With this in mind, it is reasonable to assume that the number of the Monitor of Installation 07 is $$7^6=117649$$. As well as including the number 117 when it is written in base-10 (decimal), it also includes 649. $$9+4-6=7$$.

The number 819 appears numerous times in the Marathon series. $$819/7=117$$. This tradition started in Marathon Infinity, with two secret terminals on the first and last levels of campaign mode. At first sight, these terminals seemed to contain nonsense. However, if the data from both terminals was copied into ResEdit (the classic Mac OS's hexadecimal editor), converted into text format, then expanded twice with Stuffit Expander, a map file would be revealed which could then be loaded in Infinity. The 819 was a reference to Hamish Sinclair, a prominent member of the community at marathon.bungie.org (the sister site of halo.bungie.org) as if one assigned letters to numbers sequentially ($$a = 1, b = 2, c = 3\ldots$$) then Sinclair's initials, H.S., would be 8.19.

Marathon

 * In Marathon Infinity there was a hidden multiplayer map called Hats Off to 819 (named after fan Hamish Sinclair, H=8, S=19) 819 divided by 7 is 117. (Marathon 2: Durandal has an achievement by the same name.)
 * The music for Marathon 2: Durandal and Marathon Infinity was composed and produced by an external music group called 'Power of Seven'. (Similarly, Marathon 2: Durandal also has an achievement with the same name.)
 * Two weapons in Marathon carry the 7 enigma: the MA-75B rifle, and the TOZT-7.
 * In the original Marathon, the barrels all have a backwards 7 in the serial number.

117 Trivia

 * In Halo 3, the game won't let you input the I.D. tag "I (upper-case i)-17", "l (lower-case L)-17", or "T-17" saying that these numbers are already reserved by the UNSC.


 * In Halo: The Flood, Yayap tells 'Zamamee that Master Chief must go through corridor E-117.

Internal

 * List of Biblical References in Halo
 * List of Marathon References in Halo

External

 * The Septionary is a fan-created list every seven letter word in the english language.
 * The relevant Bungie.Net forum topic is here.
 * List of "Three" References in Halo - Parody of this list at Gruntipedia.