Q-arrr is a project mainly written in C# and JAVASCRIPT, it's free.
User controlled applications on public screens.
This is a node.js application that lets users control Unity3D (and other) applications via their smartphones by redirecting them from a QR-Code to a websocket-enabled controller website. The application itself is also connected to the websocket server and can modify the controllers layout remotely.
This is a partitial result of a larger effort to make a gamelayer for reality, using qr-codes to like between real objects and digital feedback.
Check out the README in the unity folder for setup instructions.