I knew National Wonders costs increase with the number of cities you've built. What I didn't know is which that cost also increases with the number of puppets you have.
In the first image you can see Heroic Epic cost is 5670. I have 4 cities and 22 puppets, so the math is: 27 x 210 (70 x 3 as I play on Marathon) = 5670.
In the second image you can see Statue of Liberty (an expensive World Wonder): 3810.
I understand increased cost of NW compared to vanilla as you only have to build the prerequisite on 75% of your cities. However, IMO increasing the NW cost for each puppet you have makes it too expensive.
With these costs I always build the WW (if I'm ahead in science and there's no risk of being beaten) and use engineers to rush the NW!
In the first image you can see Heroic Epic cost is 5670. I have 4 cities and 22 puppets, so the math is: 27 x 210 (70 x 3 as I play on Marathon) = 5670.
In the second image you can see Statue of Liberty (an expensive World Wonder): 3810.
I understand increased cost of NW compared to vanilla as you only have to build the prerequisite on 75% of your cities. However, IMO increasing the NW cost for each puppet you have makes it too expensive.
With these costs I always build the WW (if I'm ahead in science and there's no risk of being beaten) and use engineers to rush the NW!