Before Myth, Marathon and Pathways, there was Minotaur, O:DS and Gnop. The first time I noticed a real tendency to the number 7 (or any use of the number at all), was in Minotaur. Those rune-thingies raised one or all of your attributes by 7, there were 7 network builds, etc. Why was it just then that all these sevens started appearing?
"Shortly afterwards he teamed up with another gamer and computer junkie he met in an artificial intelligence class, Jason Jones, to publish his game, Minotaur: The Labyrinths of Crete." —The History According to Bungie
Hmm... Minotaur, Seven and Jason Jones.
(Has this been pointed-out before? I hope not...)