Let's assume there's a small island in the middle of the sea with a luxury resource.
Is it worth founding a city there?
My calculation is:
- The extra resource will give me +4 happiness.
- The extra city will give -3 happiness
- The population of 1 in city will give -1 population
Which at the very start gives us zero gain.
Am I missing something or going for an extra luxury resource will not give you more happiness one could hope for?
(in civ 3 it was worth your while to grab small islands with luxury resources).
Unless there's another key tile like a missing natural wonder or a strategic resource you need more of, it's not worth self founding. It does meet the criteria to keep and puppet should an AI found it and let the city grow big enough before you conquer it.
Also if you are playing Indonesia and haven't yet founded the 3 overseas colonies if there is an empty land tile next to that luxury tile it would very much be worth self founding.
another city adds to your tech and policy costs (5 and 15 % respectively)
so you should not colonize 1-tile islands - unless there is some seafood
If you are playing BNW, that is 10% per city cultural increase, NOT 15%. Also note that as a direct result, the puppet initially isn't permanent any more, but instead is just waiting until the city both comes out of resistance and wouldn't delay construction of national wonders. (It's pretty easy post annexing to get some more culture to make up a large enough share to avoid slowing polices too much.)
If this is Vanilla or G&K, then it is the 15% per city, but there isn't a science penalty in those versions. Yes, unless you went Liberty, 15% was very difficult to cover and so an AI city with 1 luxury and 3 fish resources you conquered was usually left as a puppet forever.
1 tile luxury island with sea food and nothing else could only meet the criteria to self found if that luxury has a pantheon benefit to the religion that city will be following. Otherwise it's on the let the AI found list, let it grow at the increased AI growth rate (difficulty level dependent), and later puppet.
Yeah that adds to the penalty stack.
So I'm guessing in CIV V new city needs to pay of the extra disavanteges it creates.
Which sometimes it's not worth the extra effort...
The tactics for Tall Tradition are built all around that, you only self found 3 or 4 cities [including the capital] but they are the best city spots you know about at the time.
(The ability to defend is part of the criteria)
If desired you then attach a wide empire via conquest of the AI cities, but normally thinning them down by razing AI's junk locations and just keeping the good ones, but you can definitely win peaceful victory without conquest simply by focusing on science.