The balance of creating a world different enough to be interesting but similar enough to hold your readers can be difficult. Most writers do this by creating a human microcosm inside a created culture. The culture can be as different as you like, as long as the humans still behave in familiar ways. The "outside culture" can worship the Great Turkey and always walk backward, as long as the human beings still have relationships, problems, and deal with those problems in what we consider a logical fashion.
Every culture, created or not, has certain things in common.
Language is a human constant--every human being uses it, even those whose minds do not conform to what we consider normal. Language (or rather communication) can be verbal (auditory, and I include drum languages here), physical (tactile or visual, including writing), or implied. If someone else can get meaning out of it, it's communication.
Religion is another human constant. Every human being (except those who are severely damaged) recognizes the existance of something larger than h/imself, even if that "something larger" is only a non-random collection of microbes and minerals. Atheism is as much a belief system as any other religion.
Then we have symbolism. A very few symbols appear to be universal--two crossed lines for the cardinal directions (East, West, North, South) and a circle for the sun. East for birth, and black (or rather darkness) as the symbol for the unknown--not always death. But symbolism itself, the ability to assign meaning to apparently random shapes and ideas, is again implicit in the human condition.
These are the basics we have to work with if we want to make a culture different, but it's your characters that will draw your readers into that world you've created for them.
In essence, you build your culture around the human condition. People will always need to communicate. Define your communication in a way that supports the human condition and also supports the major culture. People will always want to assign meaning to the world around them. Assign that meaning in a culturally correct way that still does not contradict the human condition.
If you choose to break these rules, make sure that the breakage is deliberate, that it supports the story as well as the culture, and that the part of humanity that your readers look for remains intact.
And they lived happily ever after. :) In a sense.
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