It strikes me as a very weak tree overall, and a little tad bland too, just like exploration. First, many of the "moved" policies are weaker than its original counterparts, second, many of its policies have recieved an indirect nerf due to SP being easier to acquire in BWN and thus, cheapening the usefulness of the easier access to them.
Third and finally, while this is suppoused to lend you a hand into the cultural game, it fails to account that said game has changed: where are the tourism bonuses? The great work bonuses? How is recieving more policies conductive to a cultural victory now that said victory has nothing to do with them but rather with tourism?
This SP tree seems ill designed, really. But alas, let's go into a deeper analysis:
- Opener; 25% faster production of Great Artists, Musicians and Writers. Allows building of the Uffizi. => A classical era Uffizi has no sense or whatsoever, but the really bothersome thing is the other effect: this is a souped down Equality opener. Clearly inferior to its original version that helped you to produce very single kind of great person, instead of being restricted to 3 of them. Weak (effect) and a little tad nosensical wonder.
- Fine Arts; 50% of excess happiness is added to culture. => The original SP was weak already, and this further cements it since now extra culture only helps you gain more policies
- Artistic Genius: A free Great Artist appears. Requires Fine Arts. => Hard to tell how much powerful an early great artist is, but the Liberty finisher utterly trounces this one. Then again, a capped version of an already existing SP
- Cultural Centers; Monuments, Amphitheaters, Opera Houses, Museums and Broadcast Towers are built 50% faster. => This surely is useful for a wide type of empire, which is kinda strange to see in a cultural focused SP tree. Building production bonuses are extremely bland, yet this is undoubtely handy.
- Flourishing of the Arts; 33% culture in cities with a WW. Starts a Golden Age. Requires Fine Arts and Cultural Centers. => It was a really good policy back then as it is right now
- Ethics; -10% culture costs for policies. Requires FotA. => Holy SP nerf Batman! Not only the cost decrease is much less than the original version, but its value is even further dilluted by the already lowered costs of policies and penalties for going wide. Garbage.
- Finisher; Doubles the Great Work Theming bonus you receive from Museums and World Wonders. Allows purchasing GWAMs with Faith in the Industrial Era. => A nice and original bonus to have, probably one of the best ones in the whole tree
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Now, taking the aforementioned criticism into account, this is how I would remade the tree:
- Opener: 25% faster production of Great Artists, Musicians and Writers. Your palace gets 2 extra great work slots. Allows building of the Uffizi. => The Uffizi rebalance would be pending of new information, but a boost to the opener would be in order for the aforementioned reasons. A good way to do it so would be to increase the great work slots of the palace, thus giving you earlier possibilities for acquiring great work themes since it seems that the buildings with more than one GW slot comes a little tad late in the game. This way you could be messing with the themes earlier, but without them being too overpowered since there's only one palace per civ.
- Fine Arts: 50% of excess happiness is added to culture => Leave it as it is
- Artistic Genius: A free Great Artist appears. You gain one free Great Artist after gaining 4 great people. Requires Fine Arts. => A way to boost this SP without being too OP, me thinks
Cultural Centers; Monuments, Amphitheaters, Opera Houses, Museums and Broadcast Towers are built 50% faster=> Leave it as it is
- Flourishing of the Arts; 33% culture in cities with a WW. Starts a Golden Age. Requires Fine Arts and Cultural Centers. => Stay as it is
- Cosmopolitanism (previously Ethics): +1 tourism, culture and happiness in your capital per adopted SP and tennet. Requires FotA. => SP are already gained fast enough in BWN, me thinks, so why not turn the concept of the original SP around and give instead a reward for adopting more SP? Furthermore, give it a reward actually related with the cultural victory (tourism)
- Finisher; Doubles the Great Work Theming bonus you receive from Museums and World Wonders. Allows purchasing GWAMs with Faith in the Industrial Era. => Stays as it is