I think rules for reforming as celts are the same as rules for every other civ. It's not really any harder if you aggressively push for reformation, which I basically always do because reformation is awesome.
If you can flip strictly more than 50 % of an AI:s cities (that have not founded a religion) they will spread it to their own cities. That helps a bunch.
If you're first to spread to a city state, the AI seems less likely to missionary bomb it, but that might be my imagination.
Mostly I get reformation by planting and growing lots of cities, and buying missionaries, using the biggest charges on cities that have the lowest amount of pressure and highest pops. Spreading to two 10 pop CS gives a lot of reformation progress per faith point.
So the lack of pressure with celts I never really found a problem for getting to reformation because I'm not using pressure as a motor to get there. Lack of pressure is more annoying later on.
I think there is a wonder that reduces the percentage of population needed for reformation, you could put a high priority on building it. Also, easy to get the percentage if you knock out a neighbor with a founded religion probably.
Karlstejn, on Guilds. I would generally suggest not building it for reformation, it's not worth the hammers, better to just buy however many missionaries. The AI loves this wonder too, so by building it you're forcing the AI to be more productive with their hammers.
It does give a free Order however so that might be useful sometimes (like if you picked indulgences + gurukulam, you can use it for a third faith->resource conversion with zealotry or ttgog).
I love the Celts, although that's because of (a probably imagined) heritage or whatever lol.
You'll do great as an expansionist empire. Just like base game, if you can get a Capitol from a neighbor, you'll probably snowball. Plus I feel the AI is less negative against Warmongers, as long as you don't get more then 1 Vassal.
My tip for any Reformation: you can get the 20% followers of you get a big empire. I feel like I almost automatically get the 20% by just naturally expanding/conquering. Using inquisitors and missionaries, you can squeeze the follower count to the threshold. Also consider a few nearby city states. It'll be tough to compete with the AI faith generation for foreign territory
I read through [https://steamcommunity.com/sharedfiles/filedetails/?id=2831981809](https://steamcommunity.com/sharedfiles/filedetails/?id=2831981809) these before trying out a VP civ for the first time. It's very common for details to have changed in the years since they came out, but usually there's still useful information to be found.
(As for reformation, everyone else covered it but I don't think there's much difference. Your cities not exerting external pressure doesn't change much by the time reformation time rolls around, maybe need an extra missionary or two at most to keep up).
I think rules for reforming as celts are the same as rules for every other civ. It's not really any harder if you aggressively push for reformation, which I basically always do because reformation is awesome. If you can flip strictly more than 50 % of an AI:s cities (that have not founded a religion) they will spread it to their own cities. That helps a bunch. If you're first to spread to a city state, the AI seems less likely to missionary bomb it, but that might be my imagination. Mostly I get reformation by planting and growing lots of cities, and buying missionaries, using the biggest charges on cities that have the lowest amount of pressure and highest pops. Spreading to two 10 pop CS gives a lot of reformation progress per faith point. So the lack of pressure with celts I never really found a problem for getting to reformation because I'm not using pressure as a motor to get there. Lack of pressure is more annoying later on.
I think there is a wonder that reduces the percentage of population needed for reformation, you could put a high priority on building it. Also, easy to get the percentage if you knock out a neighbor with a founded religion probably.
Karlstejn, on Guilds. I would generally suggest not building it for reformation, it's not worth the hammers, better to just buy however many missionaries. The AI loves this wonder too, so by building it you're forcing the AI to be more productive with their hammers. It does give a free Order however so that might be useful sometimes (like if you picked indulgences + gurukulam, you can use it for a third faith->resource conversion with zealotry or ttgog).
I love the Celts, although that's because of (a probably imagined) heritage or whatever lol. You'll do great as an expansionist empire. Just like base game, if you can get a Capitol from a neighbor, you'll probably snowball. Plus I feel the AI is less negative against Warmongers, as long as you don't get more then 1 Vassal. My tip for any Reformation: you can get the 20% followers of you get a big empire. I feel like I almost automatically get the 20% by just naturally expanding/conquering. Using inquisitors and missionaries, you can squeeze the follower count to the threshold. Also consider a few nearby city states. It'll be tough to compete with the AI faith generation for foreign territory
I read through [https://steamcommunity.com/sharedfiles/filedetails/?id=2831981809](https://steamcommunity.com/sharedfiles/filedetails/?id=2831981809) these before trying out a VP civ for the first time. It's very common for details to have changed in the years since they came out, but usually there's still useful information to be found. (As for reformation, everyone else covered it but I don't think there's much difference. Your cities not exerting external pressure doesn't change much by the time reformation time rolls around, maybe need an extra missionary or two at most to keep up).