Here is a rudimentary, overall, "big picture" impression of Chris Langan's Cognitive-Theoretic Model of the Universe (CTMU).
Matter can be reduced to atoms, atoms can be reduced to subatomic particles, etc, etc. Eventually, if we keep reducing in this manner, we get to the most fundamental constituents of reality: information. The universe can be conceived as a vast arrangement of information: ones and zeros and the mathematical relationships between them.
At the same time, all of the information we have about the universe comes to us in the form of conscious perceptions. It is only through consciousness that we can perceive or know anything at all. Thus, our reality can just as well be conceived as a vast network of conscious experiences: perceptions and the laws which govern them.
Now, by definition, reality contains everything that exists. There is nothing outside reality. This means that its informational, perceptual content, the rules it obeys, and indeed its very existence, cannot have been determined by anything external to it. It follows that reality contains all of the conditions necessary for its own existence. Its mere possibility is enough to ensure that it generates itself. It is sort of like a self-executing algorithm that generates the mind in which the algorithm itself is known.
Although this mind (God's mind) sits in knowledge of itself in an unchanging, eternal way, it contains within it all of the processes required for it to refine itself into existence out of nothingness. As such, consciousness is stratified: the bottom stratum is the all-knowing mind of God, and within this all-knowing mind of God is contained all of the more superficial strata of consciousness that are inherent in the creation process. In other words, God is aware of all the steps in its own creation. However, from the vantage point of these more superficial strata, the universe appears as a physical entity unfolding in physical space. Our human minds are pieces of these more superficial strata. To us, things look like they are still unfolding.
And recall that our conscious minds are contained within God's consciousness. As such, we retain the creative power and freedom of God on a scale that is localized in time and space. We can choose to act in a way that facilitates the execution of the self-creating algorithm that creates God, or we can choose to act in a way that is not useful to this end, which is known as the "telos" of this particular reality. If we choose to act in a way that is in line with the telos, those parts of our minds that match the mind of God get preserved and we basically move closer to the all-knowing substratum, or the consciousness of God. If we act against the telos, what happens may be that those elements of our minds that do not match the mind of God get recycled endlessly until they properly refine themselves. The eternal unchanging nature of the overall God consciousness is preserved despite our free choices because the system continually adjusts itself in such a way that even though it is changing internally it remains eternal overall.
In short, reality itself is a self-refining informational system which, due to its form, cannot NOT exist. Even if there is nothingness, this system will exist and know itself and all of the localized conscious minds within its creation process will experience its informational structure as real, physical, etc. It is thus self-creating, as it requires nothing outside of itself to exist.
For a more detailed overview, see Cognitive-Theoretic Model of the Universe.