Here is a robot that you can use to test smartphone screens and automate app play. Tapster simulates a human finger on capacitive touchscreen devices. It is made with Bitbeam and 3D printable. It is programmed with Node.js, Johnny-Five, and Arduino.
The robot offers a tappable area of 140mm x 80mm. The above video shows how Tapster can be used to play games on a smartphone automatically.