It's certainly possible to make games without fighting in them. I was considering making a "Thief" style mod for Original Sin where fighting was also discouraged.

So the question is: if there is no fighting in your mod, what will the gameplay revolve around. Will be it some kind of find-the-item adventure game? A puzzle game?

You have not given enough information about what your mod is for people to give an answer which would actually help you. Just tell us, no one will steal your great mod idea.