Is Bioshock a Narrative?

After last sessions presentation on the Ego-shooter Bioshock the question arose whether it is a narrative or not. The answer to the question was that it is a narrative that is presenting a linear story that the player can create. Furthermore, we established that there are two possible endings to the game namely a positive  and a negative one whereas the negative ending can be further split in a negative ending with a positive tone or with a negative connotation. Knowing these facts about the ending of the game I question myself whether one can play the game multiple times. Are there so many possibilities to create the narrative that it turns out differently each time even if there are only two possibilities for an ending? Or is it a game that starts to be boring after a while because of the narrative that is fixed and cannot be altered completely?