What's different about the first run? Or is that too large a question?
I'm wondering what the best one would be, in terms of Meta Progression... It seems like Nectar and Gemstones don't appear as Chamber Rewards on the first run? Or is it just not rewards in Tartarus?
Or have I just been astoundingly unlucky, having my only source of just 1 Nectar be Dionysus?
If so, when or where do they start appearing? If Gemstones, perhaps Run 2, and maybe only on skull chambers, if my two data points are right enough.
Then there's Boons, with only Athena, Artemis, Ares, and Dionysus seeming to be available for the first run?
I assume there's further differences as well, given what I've read on the Wiki?
According to a YouTube guide by Pryde, first run Charon shops don't show any of those who haven't been spoken to.
And speaking of Chambers, Asphodel can have Food as a reward, if things go wrong / right.