it depends as with every game on the underlying principle.
What is the game about ? is it "removing" things ? is it "reaching somewhere"? is it "adding" things ? is it "collecting" things ? ....
usually you combine parts of it.
so these are some underlying principles of games. what you can boil down to "if" statements .
game levels can be created differently there are generative approaches for endless runners, or there are static approaches for ego shooters. you can mix them ofc.
But I would start with the static approach before you move on to the generative approach.
and AI .... Gg this is more complex one of the simplest form is "fly towards" where one example is A-star algorithm.
but there is meshing and perspective, movement, physics there are so many factors .... I would recommend basic tutorials and growing from there .....