Thanks to whoever recommended this show in the first place. It’s hard to find good animes. Spoilers follow.
All the world’s a stage,
And all the men and women merely players;
They have their exits and their entrances,
And one man in his time plays many parts,
The key to interpreting the show’s bizarre ending is in the name. Big O is about the simulation theory of the universe, using stage plays and film sets as metaphors. In the final episode, it’s revealed that the entire planet of Earth is a large stage with impossibly massive stage lights hanging overhead, previously hidden in mist.
Paradigm City represents Earth, whose denizens have suffered mass amnesia (“The Event”) about the previous advanced civilization but who carry the civilization’s memes and effortlessly operate its technology (which generally represents cultural capital, in this show and elsewhere, see also: AI and the Singularity as Antichrist and Rapture). Memory represents genetic memory/expression in this series. These memories resurface sporadically and elite individuals are driven to seek them out.
Like all robots in sublime anime, the giant robots represent material embodiment of souls, or “corporations”. But where Evas represent the mysteries of the human body, Megadeuces in Big O are corporations in a more gnostic sense of being a collection of people acting in unity. In keeping with the fascist ideas of state-as-god (or “emergent tribal consciousness”) and dictator-as-avatar, it is strongly implied that the giant robots are incorporated national gods driven by ingenious Great Men. In keeping with this theme, there was a war of the gods which destroyed the world approximately 40 years previously, just before The Event.
Part 2 will interpret the major characters and part 3 will hit on a couple of the minor themes.