On the matter of Neptune's gameplay, I think the puppet idea is good, it just has some mild (possible) issues in early-game strength and general compensation. For one thing, the 1% gain 2% drain outright is very painful. Even something like 2%-2% would be fine without giving her too much power as you more or less can only focus on one city at a time.

It's not the units that get me, it's the fact you are more or less unable to build early-game wonders and are struggling to get the buildings you need. This is accentuated more or less with the CBP, which during the small tests I did, Planeptune early on ended up building nothing but warriors for the first part of the game. It hurts. Even without CBP, often cities would just flat out convert production into shares or gold instead of building anything new.
I would have less issue with the puppet status if the puppet were able to keep what you were constructing while under Histy's rule, although I see how easy that would be to game by just only using her for one turn to direct the way you want.
On the plus side of this, once you've annexed a city and have Histy in control of it, production is not a problem.

Also, I should definitely mention. The mod does not scale well for timers. On standard and Marathon+, histy drains the same, regens the same, and you go through the same things for each. This is a double-edged sword as histy regens a lot faster all things considered, but also her energy is significantly less valuable as a wonder can easily be 45 turns even with her 100% bonus.

Neptune's bonuses don't all that valuable for how much of a hassle she can be. I like the uniqueness of it, and it fits her to be too lazy to be productive, but it nonetheless can be terribly unfun at times with very little reward for doing well. By finishing several quests, the only advantage you now have is an extra resource to trade, and then you're on equal footing with other civs aside from a Histy.Purple Heart's 1% per 3% feels like it'd only be effective in late game, which I'm okay with, but also I feel just makes her straight up pointless to change to if you're less than maybe 30% shares. This also creates a terrible sense of scale in a 12p game where having a 30% requires you to have a BIG edge, or often in Nep's case, multiple cities dedicated to production-to-shares, which stifles your momentum big-time.

Overall, what you have with Neptune is interesting, but it doesn't seem like it has any real payoff. It has difficulties getting off the ground, and deals with a unique mechanic that can be utterly frustrating if you end up in a bad spot (Such as not spawning near any cattle or sheep, or requiring a great general to succeed a quest, which in some cases straight up demands you declare war on someone. That's not what Nep would do, yo!).


Overall, after a few games:
Good Idea, well put together, she's not weak, but there's little motivation to play her unless you want to clip your own wings.
This giant wall of text is much less criticism as it may seem, as it is more just pointing out things I've noticed. As with anything of the sort, you can choose to listen or change anything or not, but I'd like to see her be a bit more rewarding for her playstyle's inherent difficulties.




If anyone else wants to mention anything about Neptune's gameplay, I think this would probably be an easier place to do so than cluttering the comments, as well as easier for Vice to keep track of.