The [i]Precursors[/i] of the [b]Halo[/b] universe, before the Forerunners got jealous of Humanity attaining the [i]Mantle[/i]. [spoiler]They could build indestructible buildings that stood the test of time, become anything they wanted to, and used Neural Physics. The Forerunners built Halos as a counter to this, when the Precursors who turned themselves to dust ended up with the Shaping Sickness - the Flood, in it's infancy. The Domain, the Precursor internet, really, was claimed to be repairing itself post Halo 4, start of Halo 5. Perhaps their structures may follow suit? They may not be as extinct as we think them. [b]You can close these spoilers now.[/b] ...Alternatively, the Sentients in Warframe, or the Orokin (your choice): The Sentients were built by the Orokin, but back then they were little starfish robots which could adapt to almost everything, but were designed with a weakness; using the Void as a means of travel would destroy them, if not make them unable to propagate. Eventually, they evolved a bit too much. When the Orokin came to colonize Tau, the Sentients likely took this as a threat, and followed them home. Then, the Orokin attacked in earnest. The Orokin fell, and collapsed into the current state Warframe is in; A solar system in conflict. And you are the enemy, the Tenno, of practically most of them.[/spoiler]