Well I did a little GP testing and had mixed results
I started off in Future Era...
I stack all cities with G Prophets
AI Results:
1)All started Golden Age
2) all made G City Specialists in Capitol
3) Made Pilgrimage in one city
4) Made more G City Spec in Capitol (about 5x+ G Prop)
5) Made Pilgrimage in another city
6) Made more G City Spec in Capitol (about 5x+ G Prop)
7) Made Pilgrimage in another city
8) Saved for future golden age
I then added G Artists
AI Results:
1) made Great City Specialists in Capitol only
(No special buildings made at ALL

)
I then added G Engr
1) made Great City Specialists in Capitol only
(No special buildings made at ALL

)
AI Results
Two civilizations when to War
Added both G General and G Scientist
AI Results:
1) made Great City Specialists in Capitol only
2) Saved GP to start Golden Age
(no special buildings at all; no upgrades of GG to Combat Units)
NOTES:
unknown if GP were used for TECH discovery..... Im not sure how to track it....
I did not test GM or GAgr in this particular game
Possibilities:
- Im not sure if the time era effected the way AI acted (not making special buildings)
- War could effect how GP were used
- Possibly AI would have made special building given enough time (and all other infrastructures were built first)
- Unsure why GProphet special buildings were made... and other special building were not... (possibly because they were the first GP and I flooded cities with them )
- We know in the past AI will make multiple special buildings in city (military academy and grange - ancient start) possibly future era effecting this....
Positive Notes:
I did observe AI make custom buildings (manufacturing plant/sewer system)
AI did build my custom national/world wonders
I did not change the mod from my last GP test
well I'll keep you posted
