We want to make an app to message people, but without being able to type. We will create a set of messages and responses (like those video-games with pre-made dialogue choices) that users can choose from.
Some choices will include dates and times or locations, which are too hard to do with text only, so we want users to be able to select map locations (they can only type here to search for locations) and use a data/time selector menu.
The key here is to keep the interface intuitive and easy to use, like a chat app. The place where you usually type can be used to compose messages with the multiple choice menu.
This is a concept app so we are not chasing gorgeous UI yet, but it needs to be functional and easy to expand on later.