Believe

"A hero is more than a person, a hero is a belief. A belief that, against impossible odds, the world can be saved—and that the world is still worth saving. Heroes inspire that belief in us. They renew our faith and give us that most precious of all gifts—hope. The world needs heroes. That's why, when a true hero arrives, the world will honor him."

— Xbox.com introduction to "Believe"

Believe is a Microsoft marketing campaign for Halo 3.

It features the word "Believe" as a tagline, and appears to be honoring the legacy of SPARTAN-117, citing himself as a hero of the United Nations Space Command Defense Force whose brave actions inspired other servicemen during the Human-Covenant War.

It includes handouts, live-action TV commercials, and magazine page advertisements:

• Believe (Magazine) - An advertisement in the September issues of EGM and OXM.
• Believe (Event) - A pamphlet distributed at the Projekt Revolution musical festival, featuring in-universe musical presentation of the UNSC Symphony Orchestra.
• Museum - A live-action TV commercial featuring Pawel Czernek, a UNSC veteran that fought in the Battle of New Mombasa alongside SPARTAN-117, reminiscing of his memories of the inspiring hero.
• Diorama - A live-action TV commercial featuring the John-117 Monument, a diorama of a battle between the UNSC and Covenant Loyalists, on display at the Museum of Humanity created in 2607.

A website has been created featuring the entire monument in a Flash format, in which the viewer uses the mouse or arrow keys to move through the monument. Throughout this "tour", there are many clickable icons, which show reflections by Marines who served in the Battle for New Mombassa, synopsis of enemies, vehicles, and other Marines, and most importantly, the videos.

• Museum - Live action commercial featuring Pawel Czernek, a UNSC veteran that fought in the Battle of New Mombassa alongside SPARTAN-117.
• Believe (Video) - A tour of the monument. At the end, SPARTAN-117 is seen captured. He is holding a plasma grenade. His model looks at the viewer, and the word "BELIEVE" flashes onto the screen.

Master Chief's Fate

In the monument and the videos, it is said that Master Chief has allowed himself to be captured in order to gain an advantage in the battle. He is seen in both the monument and the video holding a primed plasma grenade, and in both, looks up, indicating that he is alive. It is hinted at that this could possibly be the end of John, but nothing has been confirmed so far.