Brain VR uses the Takohi Games Text to Speech plugin,
which is $2 from the Unity store:

https://www.assetstore.unity3d.com/en/#!/content/21772

Installing that package will create:

	Assets/Plugins/Android/ttsunityplugin.jar
	Assets/Plugins/UnityAndroidTTSPlugin.dll
	Assets/Takohi/*

which should allow you to build Brain VR.
