Would a setting like this work ? (crunch)

[mekka2000]

Good lost.
Outsiders and gods from good outer planes cannot interact with the material plane anymore.
Good cleric lose all their powers, and have to give up or find a neutral (or evil !) deity to worship.

So :

- No Outsiders with subtypes [Good] AND [Extraplanar] (native are OK).
We lose Agathions, Angels, Archons, Azatas, and a few others like Cernunnos or Elysian Titans.

- No [good] spells works anymore. No bless water for example. (Cure spells are ok, as they don't have the [good] descriptor)

Will it break something I'm missing ? Is there very important spell with the [good] descriptor that could break the game if removed ?
Did I miss something else rule-wise that should be modified if "evil won and good outsiders are banned" ?

It's supposed to be a world where it's not that "Evil won", because there's many different evil (demons, devils...) and neutral forces that could be dangerous too...
As said earlier, good extraplanar outsiders don't have anymore access to the material plane, but on the contrary, all other outsiders can go freely.
So the world in invaded by devils "protecting" humanity (in exchange for souls..) against demons wanting to torture everyone.

[avr]

No protection from evil or similar means that you really don't want low will save characters in the party. Not game breaking, just to be noted.

No align weapon spell, holy weapons, holy water etc. means that DR/good can't easily be bypassed. Demons and devils invading mean that DR/good will be present often. If melee you need massive damage, if ranged you need clustered shots, and mundane armies will be slaughtered.

[Bob Bob Bob]

No Planar Binding devils/demons, since you can't use Magic Circle against Good to trap them.

No Bless Water I think means no Holy Water? Since the only way listed to make it is the spell. So low level players will need to run in terror from ghosts (something they should already do, but still).

As avr said, no Protection from Evil makes the charm demons/devils much, much stronger and a good Will save even more of a necessity.

Would the change also affect magic items? Because even without the spells you can make them (a Holy weapon is only a DC 22 Spellcraft even if you don't have any of the prereqs). That will probably break something, but I couldn't say what. Lots of magic items have somewhat arbitrary prereqs, there's probably an important one somewhere that uses a good spell.

[Ascalaphus]

What about paladins of LN deities? The Celestial Bloodrager bloodline? If DR/good is going to be a hot issue, you should have answers to those questions.

That said, I'm not 100% sure about [good] spells. Magic Circle vs. Evil is a staple of evil wizards setting up binding circles to negotiate with demons/devils for example. And since it's arcane magic, it's not like it's actually power coming from Above anyway.

[mekka2000]

Magic items were made before the banishment of good, so there's Holy weapons (now even more precious) and bane weapons (so, +3 weapons with bane can be +5 and bypass DR/good).

These things are rare (the sort of things that only PCs seems to find :p ) and acquiring a holy weapon could be a quest by itself.

Not having an easy way to bypass DR/good is one of the reasons humans surrendered so easily to devils, accepting their protection against demons.

Life of PCs will be hard and they have to stay mostly under the radar of high-CR demons.
That's the mood wanted, and it's supposed to be E8 too but with 3 mythic ranks max. possible, spheres of power magic, path of war, akashic mysteries and psionics.

[mekka2000]

Ascalaphus, good point about non-divine good spells.
What if good spells couldn't learned by level up but only by finding it on scrolls ? Let's say Wizards cannot be inspired by "pure good" by himself but can read a learn a scroll.
And for sorcerers and bloodragers, good spell only with a compatible bloodline (celestial).

[bitter lily]

Spinning off questions...

What are the aasimars doing? Are they especially hunted? Do they have any power (feats) anymore? Can they access good spells if arcane casters? For that matter, do the Celestial sorcerers & bloodragers have a "smell" that the evil outsiders can pick up? Are they especially hunted?

Can witches (my favorite "good" class) have their familiars learn good arcane spells from another (older) witch's familiar? How long ago did good lose, anyway? If less than 40 years ago, it would be quite possible that witches still had Cure spells and a few others. And what happened to those mysterious Patrons that provide witches with some of their spells? Were any of them "good outsiders"? Or are there supernatural forces working for good still active -- and coming on strong in the absence of the good deities?

What are all the clerics of good deities doing? Are the churches still in place, though offering only mundane help? Are at least some of the clerics fighting back (mundanely)? In short, is there an organized resistance to evil winning locally? Are there bandit bands of disenfranchised clerics?

What kinds of laws are being passed now, in the devil-held lands? Who are the nouveau-riche in this grim world? Who are the aristocrats losing their wealth and maybe positions in society and maybe their lives?

[Carick]

Midnight is a campaign setting published by Fantasy Flight which evil has in effectwon.
This is a game which is close to what you are looking for and it can still be found for sale on both ebay and Amazon.

Midnight: Epic Fantasy in an Age of Shadow [d20 system] by Jeffrey Barber, Wil Upchurch (2003)

[Ascalaphus]

You can probably also steal some material from Ravenloft.

[SmiloDan]

Can you use Magic Circle vs. Law against devils and Magic Circle vs. Chaos against demons?

[Inlaa]

Honestly, to go full-on depressing setting, I'd get rid of magical healing (cure spells) too, sans the evil ones (like the Infernal healing spell wizards get). Reasoning: this makes the Heal skill important, and you could buff it for it to be more of a centerpiece in your campaign. Suddenly, a Rogue or Wizard with a high INT that dumps points into Heal every level is the party healer.

[SmiloDan]

Removing magical healing from PF REALLY changes the game play.

[Inlaa]

SmiloDan wrote:

Removing magical healing from PF REALLY changes the game play.

It does. I've played in low-magic games where magical healing was non-existent and it was some of the most fun I've ever had in the game.

Also some of the deadliest fun. My poor friends...

#NeverForget

[SmiloDan]

Sounds like Dragonlance.

[Particle_Man]

Can characters travel to the outer planes? If so, are they barred from reaching the "good" outer planes and meeting good outsiders there?

I assume that if good clerics can worship neutral gods then paladins of LN gods are still ok (and of course anti-paladins are going to be just fine). That said, there would likely be fewer of the divine good guys. Or do you even require clerics/paladins to have gods? I assume that you do from the text of your OP.

If you do allow paladins, do they lose Smite Evil? If so, not good for the paladins. If not, they can beat the DR of demons and devils. I believe Inquisitor judgements can also beat DR (unless that is stopped as well).

If you do require god-worship for clerics, and only use the pathfinder gods in the phb, I notice that with access to "Good" lost you also lose the Community, Liberation, and Sun domains (and thus their subdomains). But that may be a feature rather than a bug for you.

Probably finding a way to raise the barrier to good outsiders/gods would be a major concern of the good NPCs with any power. Not saying they would succeed but they would likely put resources into that.

Summon Monster X spells tend to be heavy on the monsters being good or evil (celestial or fiendish), so in this brave new world it would tend to be an evil spell summoning fiendish critters.

Is your world going to focus on a Law vs. Chaos battle, now that Good has been defeated? Or are the remaining Neutral Gods going to try to form a bulwark against Evil?

Is Rovagug now more likely to break out, since there is less divine opposition? I think the backstory is that EVERYONE dog-piled on Rovagug to lock him up, so without the good gods, that is a lot fewer of everyone.

Where do the souls of good mortals go now? Presuming this could/would be known, it might determine whether mortals still aim to be good and get to Heaven, go for reincarnation, or cut their losses and sign up with an acceptable neutral god.

Undead are harder to deal with now.

Wait, are you allowing neutral clerics (or good clerics of neutral gods) to channel positive energy, or would it all be channelling negative energy (possible for neutral clerics)?

Do good clerics of neutral gods exist in your world?