I finished another game via showdown a few days ago, and was, in the process, rather surprised.
Here is why: 763AIP, single world chokepoint, lots of active golems, 8 champions.
The surprise: the AI waves were... a bit on the small side.
Now, this was ultra-low caps, but even then, waves less than 500 with all those golems, AIP and champions?
Also, the Exo-galactic attacks, apart from the GCS waves at the end, were pretty tiny- maybe one or two dire guardians at most, certainly no golems- which just disintegrated as they hit the defences. The only thing that took a bit of killing, and even then didn't stress the defences, were the Special forces release and the GCS itself.
Comparing this to the first showdown I did, with no golems, half the AIP, (Admittedly normal caps) resulting in things like golems in every exo-wave, and far, far higher number of incoming ships, this seems a bit... feeble.
I had already killed one AI home command- is that why?