If you were a VC/developer, what questions would you ask for an app idea?

Pretend that someone who is not at all technically inclined as far as development is concerned pitched an app idea to you. They are genuinely excited for the idea and that gets you excited for it as well.

What questions would you ask them, besides "what does the app do?" before you decided to fund/develop the app for them? Think of a checklist of items that you would ask anyone who would pitch you the idea.