"Are you blue or green?"
Translation:Mavi misin yoksa yeşil misin?
just adding to this, "Mavi misin yoksa yeşil misin? and Mavi veya yeşil misin?" are not the same. In the first one you are either blue or green, and you are asked which one of these you are. In the second one you are asked if you are one of these, or if you are a third color.
Are you talking about some hidden context that we are missing, or do you mean it just "sounds wrong"? Your explanation above seemed to make perfect sense until I read your second comment.
E.g.: I am playing a game with 4+ players, and have to interact with the players of blue and green. I forgot who was playing what color, and I ask the player next to me: "Are you blue or green?" - meaning: "Do I have to speak with you, or with the other players?"
That is how I understood your above explanation for the use of "Mavi veya yeşil misin?"