Timeline

2007 - Bungie announces it is becoming an independent studio separate from Microsoft.

2007 - The first ideas of "Destiny" begin to take shape.

Multiple iterations are done with the core idea of a shared-world multiplayer experience. While the game takes a number of different gameplay and universe ideas, it begins to iterate closer and closer to a sci-fi FPS (like Halo).

2009 - More of Bungie begins to work on Destiny, as Halo: Reach nears completion.

April 16, 2010 - Bungie signs a publishing contract with activision.

The contract stipulates four Destiny game releases and four expansion releases between 2013 and 2020. Read more about this legendarily bad contract →

September 2010 - Bungie ships Halo: Reach, at which point the studio becomes fully focused on Destiny development.

October 6, 2010 - Joseph Staten mentions the idea of a game with an "infinite storytelling horizon" at GDC Online.

February 17, 2011 - A fired contractor leaks to Kotaku that Bungie's new game, Destiny, is a sci-fi MMO.

March 3, 2011 - A Bungie developer at GDC mentions the next Bungie game is an MMO, though Bungie downplays it.

August 4, 2011 - Project Tiger mentioned in a 20th Anniversary ViDoc, along with the Destiny logo.

May 12, 2012 - Bungie/Activision contract is revealed to the public.

November 6, 2012 - Kotaku reports on an accidentally-public blog by middleware publisher Demonware about the game.

This confirms a PS3 version and 3-player online co-op with a persistent server, plus drop-in-drop-out “public areas.”

November 28, 2012 - Destiny story details are leaked to IGN and Kotaku.

These end up matching the story details in the reveal event for Destiny 1.