Np! Let me know if I can help somehow.

Good night.
I would love to post a long response, but there's one thing I forgot to say. It's highly important we don't leave what the world is ambiguous. For instance, if the world is Earth, then we will likely be confined by legends/myths/history of the real world. It is pretty much accepted by the Fate verse that gods do indeed exist, but no longer do they live by Man. That ended with the Age of the Gods, Babylonia version. So, if we're going by Earth being the setting, the gods likely do not interfere much with humanity and what it does. 
For that reason, I think it's more likely we go with the Forengard-based version of Earth. We're pretty familiar with it, can be free with our imaginations, and it's more likely the timeline and such work in our favor. The magic system would also reasonably be different, if there is an universal one at all. And most importantly, deities would probably be existent.
However. Just because deities are existent doesn't mean that I think they should have as active as a role in the world as they do in GGaD. If they do, I would definitely love an explanation for it. Deities and demigods are definitely OP (,,, my demigod characters can be, anyways), so at the very least, I don't think they should be able to interfere with the world easily. If demigods can still actively be born in the world at this point, which depends on the status of the deities, then I'm supposing they are more like mages than gods if they do practice magic. And if demigods have been heroes in the past, I'm guessing they're eligible for summon but might be very hard to summon. Or something like that. It's 1 A.M. and my brain has unmiraculously self-fried.  
The way my mind was kind of going was that it's unlikely mages would be so fervent for discoveries and improvement if it were so easy to gain access to deities' help. That's my opinion at least. The Age of the Gods in the AU might have lasted much longer than it supposedly did on Earth. It also might have ended differently, which I think is likely if we're going this route. I'd even like to think that the Grail War and other similar occurrences have something to do with the gods. Just thinking...if we go off the path of magicky magic to explain how the Grail can grant wishes, who else could grant wishes? Probably the gods. Who could revive Heroic Spirits? Probably the gods. Who could make sure those Heroic Spirits are actually heroic and bastards like Gilles de Rais don't appear? Yeah, probably the gods. I'm probably biased, though, since when I say "the gods" for the last two, I kinda mean a god of life or something along those lines, as well as similar existences. :D
Reminder to myself to respond to the questions I posted once we get this sorted out.

-Galaxian-

It's just what it is. Forengard mostly seems to be interpreted as a planet, and it wouldn't be able to sustain life (disregarding the influence of deities) if it weren't like Earth. That's not the way I interpret it, but it's the logical way to go for this. Specifically, the time the AU is in would be the modern sect, with the medieval sect having already "happened" rather than it coexisting with the modern sect, as it is (or seems to be?) in GGaD canon.
I'm not too much of a fan of the Age of Gods ending with gods being like "bye bye humanity" and just leaving, like how in Greek mythology they did (with Astraea being the last one to leave iirc). I'm not quite familiar with all cultures, but in Fate, it's stated that Babylonia's Age of the Gods ended due to a variety of factors--when Solomon died, when Babylonia fell, and in 700 BC due to unknown reasons. Buuut, in Chinese culture, there are no references to the deities dying or disappearing from contact with humans. Even though the Chinese are/have been mostly atheist, there are deities being referred to in all paths of mythology. So, I don't consider "the Age of the Gods," or specifically its end, to refer to Chinese deities even in Fate canon.
I guess it depends on planning how the Age of the Gods' end actually worked and what it means now. For instance, when it was, where the deities are, if they can be summoned as Divine Spirits (or if the system is a bit different in the AU), when the end of the demigods came, etc.
I was more thinking that if deities are involved in the Holy Grail Wars, it's likely that only the deities with related domains really have any control over it. Personally, for a certain life deity, I was thinking that he harbors a bit of control. I actually personally headcanon he was the one who enforced the rule that the dead shall not influence the living, and if the rule is broken, I think Heroic Spirits will have much more difficulty existing and/or certain components about them (stats?? Spirituon cores?) are changed accordingly. But mostly he only supervises (if that's the word) the "life" aspect of the Grail Wars. Otherwise, I would think that the primary overseers of any Grail War would be those related to wishes and--primarily--magic. There are a lot of magic deities in Forengard, after all, and I think that fact would make sense in the AU, lol. Of course, there are more deities (like I kinda thought about Heroic Spirits having connection to a certain deity of ghosts), but yee. 

-Galaxian-

In GGaD, my characters use "Forengard" and "earth" (uncapitalized) interchangeably. For instance, they could say "What on Forengard?" or "What on earth??" It's just that they don't say "Oh my God" they say "Oh my gods." Or stuff like that.
For some reason, it feels like most deities don't withdraw influence over humanity/Forengard unless they're literally forced to. Then again, I also have a deity who's incredibly involved with human affairs. Most other deities seem to prioritize their own lives first, while my deity is like, "Kinda actively dying but I'ma help the humans first uwu"
Divine Spirits are said to be the highest variation of Nature Spirits, which kinda interests me because that makes me think of Germaine and Youri. Even if I'm misinterpreting it, I don't think I need to stop misinterpreting it like so, because maybe thinking of it in that way is helpful. Anyhow, most Divine Spirits don't appear in normal Grail Wars, yes. 
This somewhat lacks a transition, but specifically for the life deity, I was thinking of how in GGaD there's not really a single belief in one god (though some focus on one god, e.g. Novaspawn focus on Nova as their one god even if the other gods do exist; they think of Nova as superior or the true one or smthn, I kinda forgot what Xenon said), so unlike Fate, where most Rulers are Saints/Holy Knights/related to God, in the Fate AU it's more of a...well. I'll just cut to the chase, haha. I was thinking Galaxian is an eligible Spirit for Summons, but not by a human. He's a Ruler! If the "you shall not influence the living" rule is excessively broken or he can clearly project it as a future event (via prophesy), he likely appears. He's a bit different than canon Rulers like Jeanne in Apocrypha, though. He likely actually manifests by himself via the Grail (rather than the Grail manifesting him) and he isn't compatible with any host, so his form is different than Servants'? I'm not sure how to explain it, but I guess Ruler would be the only Class he's eligible for because it wouldn't be fair for deities themselves to participate. Anyhow, it's not like we can see Galaxian in this AU, specifically the part we're roleplaying, but he probably has a more active role than most deities because of his choices. I'm not sure how his abilities are balanced to the extent of Servants (so he doesn't, like, destroy the concept of Ruler by just being able to go "Sayonara :D" on problematic Spirits' existences) but it's a concept in the first place, so xD
I said "I kinda thought about Heroic Spirits having connection to a certain deity of ghosts"
To figure out related questions, we probably need to think more about the magic deities. Again, Time isn't in the AU, so he can't confirm this. But looking at GGaD canon, excluding Annette, the (active) deities of magic (who I'm familiar with) seem to be mostly mortal-born. Time, Chronos, Kenshin, Rune.
I'm not actually sure about the origins of Ark and Drago, though it does say Drago was born to humanoid parents even though she's a hybrid, for "unknown reasons."
Anyways, I'm not sure how to say this, but I guess if those magic deities (and presumably others) were mortal-born in the first place, perhaps that's something important for lore, related to the Age of the Gods, maybe, and the Grail. Perhaps magic itself is a way to try to become a deity, not just to imitate them. Who knows? I just know that I can't say much for my deity's end, since he was never a human. 

-Galaxian-

In Galaxian's case, he constructs his own form, like he does in GGaD. Funnily enough, I think his stats would be pretty bad save for a few, at least compared to even the Servants here. Like, this is a prototype come up with on the spot, but probably something like:
Strength: D
Agility: A
Luck: E
Endurance: EX
Mana: E

Probably in a way that's less dark. In Fate canon it had to do with the Grail manifesting as Heroic Spirits/Servants disappeared and returned to it. Maybe here it has more to do with magic in addition to that.

I "[think] about  Heroic Spirits having connection to a certain deity of ghosts" :D

Who knows? Maybe mortals doing Grail Wars has benefit to the deities. Maybe it's to find out something deities don't know themselves, or can't do themselves. Maybe that's why the deities are interested/invested in it, at least partially. Related to magic? Or on a larger scale, related to the deities' origins, which if found out could perhaps make for greater power for the deities or to break the stalemate of how they've been unable to interfere with Earth for a majority of the time for a long time? Who knows. Many possibilities exist.

-Galaxian-

He probably has stellar skills though xD stellar is a pun hehe
I guess I'll let you think, lol. I don't particularly like to spew out ideas to others if they're not going to give feedback at the moment.
Did I say that? Maybe modern magic is sourced from the deities. Not necessarily "magic" as a whole, though. That's left up to debate.

-Galaxian-

I had some thoughts to share but they've fled from my brain xD. Let's see what I can remember here.

I'm not sure if you mentioned this earlier but, do we have an idea of "where" the deities are at the moment? I thought perhaps some of them (probably only the ones related to the whole Holy Grail War thing) reside inside the Grail or something, although they can't influence external events. I think it could make sense because then it kinda explains where they went and why they're not active, though I have no idea of the reason for this and I need to put more thought into it. Having the Grail be directly related to deities grants it the title of "Holy" too. I mean, it already has it, but it would be nice to have an explanation.
Going a bit with ^ that idea, maybe the Holy Grail War has been happening periodically after the Age of Gods ended, but idk. I just like the idea that the one we'll be roleplaying hasn't been the first one to happen. Maybe by achieving something like "true magic" it would establish the perfect link for deities to return to the world, like you mentioned. It could be that it hasn't happened because of failed Wars and selfish wishes tho?

I also wanted to mention that maybe this AU Grail doesn't need all 7 Servants to be sacrificed? I don't think we've determined any second or "major" motive for the War yet other than the wish, but if we're assuming that out version of the War is "purer" than the one shown in canon Fate, then it wouldn't be necessary to force the last Servant to sacrifice themselves for their Master's wish and instead would allow a pair to get both their wishes granted. Does this make sense? 

I'm sorry if the style seems kinda choppy, but I'm tryina gather bits of thoughts together and it's being really hard :') so I'm definitely forgetting some things I wanted to add in there, but as always, I'll tell you if I remember.
 

Okay okay, I'm pretty sure I haven't established enough context for saying this, but my mind just kinda summarized it. So here we go.
Putting aside details for the Age of the Gods--the general idea is that the deities can no longer interfere with the real, mortal world. Even if Galaxian manifests as a Ruler, he upholds the principle and merely makes sure the dead don't influence the living. That implies the fact deities can't interfere with the mortal world is also a cosmic principle. 
Now, it can be presumed that the deities as a whole want to get back in touch with the mortal world. That's where a past component comes in--the fact that the mages might want to become deities. My idea is that if this is indeed their wish, then it might be because for all of the years the deities have been separated from humankind, no new deities have appeared. For a new deity to appear would mean an almost instant connection between the mortal realm and the immortal realm. The Master would be the connection point.
Now how to achieve this? Well, to be honest, the deities themselves might not even know. And here I'm noting two things. One, for a mortal to become a deity, GGaD says an ambrosia flower must be used just before death. Why do ambrosia flowers appear and why can they cause that effect? No one knows. Perhaps in this AU, it's related to magic? And perhaps to lore? I'm against keeping the ambrosia flower as a highly important concept in the AU (I feel like it's boring, I'm ngl. That's why I never had a mortal-born deity), but maybe it symbolizes something. Two, in general, Heroic Spirits are likely the ones closer to the gods. I'm thinking that possibly the Heroic Spirits in the AU are those who were present in the Age of the Gods, not any heroes after. That might seem weird, but it makes sense to me for some reason. Because I think, the gods are more connected to the heroes in their age and thus are more able to summon them into the mortal realm (which they have difficulties accessing), and also, I think the connection from the Heroic Spirits (when they were living) and the gods may serve as a further catalyst of some kind.
And I thought a bit too much, so back into vague territory I went. Lol, sorry. I originally was thinking only of the Masters for the concepts above, and then I thought more about Servants. I guess it might be possible that any Servants from after the Age of the Gods wouldn't connect to the gods' purposes very well, and if Servants' true roles are to somehow guide mages to the point of becoming gods (or so it seems), then people who never saw gods can't ever do that in the first place.
I swear I didn't make all this up to make the entire Modern Sect atheist lol I swear

-Galaxian-

Oh yeah, and it would be useful if you could brainstorm/infodump directly into this thread so I can check that out and reply too!

Ok, np! My brain is short-circuiting rn lol so I'm actually going to sleep early. I'm sorry if this reply doesn't make sense thanks of to that. Be sure to tell me if I missed replying to any parts of your posts! And yes, be more responsible than me and work on your hw.

Ok now to the actual answer lol sorry. I feel like saying just "I agree" and not discussing is not enough, so I'mma try to not do that. I don't want you to feel like I'm leaving everything to you tbh.
But really, reading in more detail the post you made before, I like what you're proposing. 
This is a bit more related to my own thoughts, but do you think that the equivalent of "reaching the Root" in this AU is "gaining a deity's power"? I mean, since mages tend to be concerned with becoming the most powerful they can be and stuff.
I still don't know what the Ambrosia Flower could do/mean but its being a symbol sounds pretty cool. I'll see if I come up with any ideas about that lol. 
I like the idea of heroes from the Age of Gods being summoned. Is that completely ok with you tho? I'm good with going with it if we continue with the headcanoning in that direction.
The Modern Sect being mainly atheist makes sense though xD. I'd think that a few people (probably more experienced mages or something) at least have knowledge of the deities' involvement with the Grail and their past role, though this "knowledge" is likely to have been tinted by legend to the point in which they don't have any solid facts and instead just vague ideas that seem like the truth and work out. Like, I doubt they completely know about the deities' purpose of returning to the world, but they're probably aware that the Grail is a connection between the divine world and the human world.

I have no idea of why Kiritsugu got the Command Spells that early tbh. Perhaps it had something to do with the fact that the span of time between War and War back then was longer? To be honest I don't know so all I can do is conjecture. It's up to you if you wanna make it happen, so I'd like to hear your opinion(s).
"Failed" isn't really the correct word but it's the first thing that popped into my mind so I used it. Apologies about any misunderstanding it may have caused.
Going a bit with canon, any chance that the act of "sacrificing" the Servants might strengthen the deities enough? Along with the mana mages expend during the War? Even if slowly, maybe, maybe by the time many Holy Grail Wars are successfully finished, maybe one day deities will be able to have enough power to come back. Idk. Maybe in that case the best outcome for the deities would be to not have a clear winner, as a winner would mean that some of the mana has to be sacrificed to fulfill the wish. If there's no wish, they just keep the mana. How does this sound?

And lol this might sound wild but something you mentioned earlier gave me the idea for this: What if Spec is the Grail? Like, idk, but I think that their being the Grail would provide a path for Heroic Spirits to come from the Throne of Heroes (or the equivalent in the AU) to the physical world, and also gather their essences back. They could very well assume a form like the actual cup too because they don't have an "official" appearance. Idk. Please tell me what you think about this xD I'm not very confident about this idea and I think I didn't explain it very well. 

How's your homework going?
This is a completely subtle proposal to go on chat and have fun and do stuff lol, sorry if I'm being too insistent.

If you interpret it that way, you're free to do so. I don't see much of a parallel between that and what's happening in this AU, so I've chosen not to think about it that way.
Though, for some reason I feel like there've been winners of the Grail War who've been like "Make me a deity!" and the deities are like "Bruh so close yet so far". Overall the association of the Grail with power makes sense though; it's probably pretty hard to win a Grail War to start off, and wishes have been proven true (I think deities can give others powers without much issue), so that's why they keep occurring.
This is up to interpretation, but yesterday night I thought maybe the deities give around 2 generations' time for a Grail War to start anew, to see new potential and new stuff happening in general.
Tbh idk how the deities choose which Heroic Spirits to take in and how they took them in in the first place. My mind is a bit more complicated for this topic but ig,,, idk, maybe it's the thought of the heroes and deities coexisting at one point making my mind jostled a bit. Maybe it's the fact that in Fate, there's a Throne of Heroes? Maybe some deity of heroes/bravery/courage/achievements (something along those lines) acts like the Throne in this world.
I was also wondering that if the process is more important than the end to the deities, how exactly that process is supposed to lead to one becoming a deity...more planning needed, ig. 
We also need to specify further just what people now about the Grail.
I'm not sure how the disappearances' of the Servants would strengthen the gods, so if you're thinking in that direction, you'll have to justify the correlation. I think that the longer a Servant survives in the Grail War, though, the connection between the immortal and mortal world becomes stronger. So maybe the Servants living is actually important, making all the Servants dying unappealing to the deities. For instance, if all Servants are somehow all surviving, that means they're all pretty strong, and so the number of links that are providing the connection makes for a stronger sum of connections. Of course, once it comes to only one Servant living, I would think the connection might be at the strongest. By then, the strength of the Servant might have to do with the Master, instead of the Master being the one to supply power to the Servant. I dunno if what I'm saying is making sense, but some of this basically reverses what Fate had and changes it in another direction.
I'm not sure if humans' mana could strengthen the deities at all. For some reason, I feel it's unlikely, but I don't want to seem like I'm striking down literally every one of your ideas. Perhaps it could be of some sustenance to specific deities, like those that deal with magic. I'm not sure. I feel like my interpretations of magic might be getting in the way for this one. For instance, I think Time and Chronos could probably get the mana, but for other magic deities, like Kenshin with his dark magic, I'm not sure if he even works with mana.
I don't feel like achieving the goal of returning back to the mortal world is a time issue. 
Funnily enough, it seems your idea with the least confidence from you is the one I'm having less issues with. I'm fine with that. Like I said yesterday in chat, they possibly are the only True Grail, too. Going on with that, I was kinda thinking of Galaxian being the true Ruler paired up with the Grail, so the Grail acts more like a channel than the Grail just summoning a Ruler in Fate canon.
I wonder what the two of them think about this entire thing going on for them. 

----

No problem lol, she's really efficient for farming

-Galaxian-

I'm not sure what you're replying to in the first sentence of your post so I'll just leave it there and hope it isn't something too important. 
Ok about the giving deityship though, I think we agreed it's not possible for that wish to be granted like that, right? 
About how much time is two generations? Uhhh 150 years aprox? The canon span of time between wars is 60 years, but I think you already knew that. Well, I think the reason for waiting two generations' worth of time is legit. So that can be official if you're ok with it :3.
Hmm... the idea of a deity acting like the Throne of Heroes, maybe they actually collect records of the heroes and their legends from all over time, but it isn't necessarily that all of them are from the Age of Gods. Just now I thought that perhaps it's easier to summon the heroes from long ago not only because their legends have been around for longer, but they also are more likely to have interacted with deities and so they would work better as potential links between deities and the world. Maybe that goes to the point in which it's impossible to summon a more recent Heroic Spirit unless there's a good catalyst for it?
Yeah, I don't have much to contribute to that specific part of planning atm. I think I just need a little guidance there to kinda see how your thinking goes and so I can try to brainstorm stuff.
Well, for sure they know that it can grant wishes. I guess some might know it's an artifact connected in some way with the deities, but I dunno if they'd know the extent of that connection. I don't think everyone knows about the Grail's existence though.
I just suggested that part about the disappearances as a kinda reference to the Fate canon, so I gotta say that I wasn't really thinking anything specific about it xD. So, I can't justify anything there. But, see, just mentioning it made another possibility pop up. Ok but here the thing I'm having a bit of trouble imagining at the moment is the relationship between Servants' survival and the Grail's materialization. I guess it's different here because of all the changes we've made to the system though. The thing would be that I think that there probably is a rule that only the winning Master-Servant pair can claim a wish, so then, what happens to the other six pairs? They've surely been defeated, and that means that there might be a bit of a flaw in the way the connections are done. Uh, like, the connection would be at its strongest when all Servants survive and that's what deities want, as you said, but then that could mean that the Grail can't manifest to grant the wish to the winner and establish a firmer connection. Unless I'm getting something very wrong here. But don't worry lol this is just thoughts for you to discuss and refute.
Ha, don't worry about invalidating my ideas! That's why I'm better at working with others in the first place, so they can shoot down the ideas that aren't worth thinking about in order to keep the best. But, well, in this case I think I didn't say it very well (and there's no problem lol I think I myself am having a bit of trouble trying to wrap my head around this concept in a way that makes some sense) but I didn't mean really that the deities were directly strengthened by the mana itself. I was thinking more of a "connection" of sorts, but that concept is super hazy in my mind so I can't provide any supporting details for that idea. At least we know that the mana is used for Servants though, right? Maybe that's its main use. In Fate canon the Grail gathers mana to fulfill the wish, but as we have deities involved here, it probably wouldn't be needed for that purpose. 
Okay then! So it isn't a time issue... then what is it? I'm fine with leaving this undefined, even if it's just for now.
Lol ok, then Specter's the True Grail! I'mma see if I can come up with something about it that's worth discussing lol all day my mind has been giving me these images of the Grail with Spec's hair and face and also Spec with the Dress of Heaven and to be honest those mental images are kinda cursed. 
I'm not sure of what they think. Defining that is up to us, I'm pretty sure. What do you think they think?

And thank you for taking the time to reply to this even though you're busy. Continue focusing on your classes, dude!

Lol just slap me or something xD serves me right lol it's probably because my mind isn't grasping the concepts very well. I think it'd be helpful if maybe a couple posts later we can summarize what we've got so far or else I am going to get my brain short-circuiting for real xD.

Ok. I wasn't completely sure about that xD.
Bruh lol I know a generation is like around forty years or something (33 from what you're saying) but I understood it the wrong way. Anyways, 66 years it can be if you want (:
(The smiley face isn't supposed to be creepy btw)
Bruh number two xD ok.
Okay! I hadn't thought of that part so yeah it's a good point. So the less Servants the better, then.
Mana = anchor, then?
Ok lol you do sound kinda cross in that part of your answer xD. Lol ok I'll keep it in mind though.
They're helpful...? o.o. 
So... Ruler kinda shows up like the woman in the Grail from Apocrypha? Kinda like that? Or are you thinking that he materializes outside the Grail?
I dunno very well how to direct my thoughts about Spec, but I was kinda thinking that they probably don't have an easy way to show a physical form due to being the Grail. Their consciousness might be reserved to a "mental space" or something. Like, not physical, and it's not that easy to contact either.

Well, I also find it fun xD It's just not that fun when my brain repeats information though :v.

I'm not sure what happened I think my mind went like "80-ish years is too short???" and I tried to come up with another meaning for the span of a generation.
Hmm, maybe it wasn't that clear for me then.
¯\_(ツ)_/¯
Ah yes, I couldn't remember her name atm. Coolio! I think it works though.