how to make your own AI

how do you make an enemy AI without using scripts that are already supplied by unity. thanks in advance.

Your question is very broad and non-specific. I suggest you have a look at this questions and its answers:

AI Programing Resources

You can also browse the highest-voted questions with the ai tag.

i don't want to repeat what others said. for creating AI you can use one of these ways 1 there are complete solutions for behavior trees, path finding, steering behavior and ... available. take a look at angryant's website 2 use DLLs or create your own dlls and call them from unity (pro only). this is good for complex codes that they need much speed. 3 create your own C#/javascript/boo scripts in unity. to learn how to create the ai for your game you can go to websites related to "ai for games"