Thread:$17/@comment-4851119-20140707142736

Well, I've got the basic idea down for now.

The galaxy is ruled for countless eons by the Old Ones (fusion of 40K War in Heaven Old Ones and Lovecraft's Great Old Ones) until approximately two hundred thousand years before the present time. Along the way they uplift the Forerunners, the Celestials and the first human civilization (the Culture) as heirs to their empire.

At this 200,000 year mark, the Xeelee stomp the old ones while looking for a forgotten superweapon to help in their universe-wide losing war with the Anti-Spirals and the Daleks. They don't find what they're looking for so they leave after the stomp is done. The Old Ones grow old and jealous as their empire collapses and leave a number of hidden purge buttons behind to wipe the galaxy of life, such as the Flood, The Beast and the Markers.

The galaxy falls into chaos for fifty thousand years or so, including the rise and fall of the Protheans, the Rakata, the Necrons and DAOT humanity. Humans (the most numerous species because they were always the Old Ones' special favourites) end up scattered around the galaxy when the empire collapses and most tech goes away. Each human remnant gets a mixed bag of tech (Supcom and TA humanity get a lot of the nanotech stuff from the Culture era, Mass Effect humanity gets almost nothing and has to rebuild from Prothean leftovers, etc).

The fall of DAOT humanity (fused with Dune humanity) about 150,000 years later marks the gradual calming of the pan-galactic shitstorm. The various humans and aliens that were nuked into the stone age during the Xeelee War and kept there during the shitstorm finally crawl out of their caves and start rebuilding. For the next one hundred and fifty millenia there is relative stability, marred only by a lot of small wars and a few major ones.

However, as of the present day there is a cold war engaged between the CORE, the Citadel Council and the Covenant, all of whom are poised to fire their galaxy-fucking superweapons at a moment's provcation. The CORE know they can stomp the others in a matter of days, but that's long enough for the Crucible to knock every mechanical-tech civilization in existence back to pre-industrial levels, or the Halo array to wipe the galaxy of organic life, which would bhe devastating blows to either them or their allies; the only thing they have in response is the use of the Implosion Device. The Tyranids, the Vong and the Reapers are pouring in on all sides, and the dread powers of Chaos are stirring en masse for the first time since the Old Ones fell... 