ARCore, AR platform for Android, was announced from Google at the end of August. As written on the following site, ARCore can track position and orientation of smartphone without using marker detection, and can detect horizontal plane such as floor or table.
However, due to only one provided sample, in case of creating contents expressing falling object staying on the floor, some programming skill is required. (as of 2017/9/19)
So this article introduces how to create AR content wich interacting horizontal plane and object with editing basic sample.