Here is another biofeedback device that helps you understand how your brain responds to your thoughts and actions. HEGduino shows your brain blood-oxygen levels in real-time. It can be used to perform brain exercises, monitor stress, and try advanced biohacking. The HEG supports interaction via Bluetooth, WiFi, and USB.
You get a game that runs on HTML5 compatible devices. Since this is an open source platform, you can modify HEGduino and its app to fit your needs. The developers are working on a free mobile app for this kit too.[where to get it]