BVOVB developers do not collect any data however as every Unity Personal Edition generated software the Unity Player will try to collect and send some hardware and software information. We suggest to read Unity regulation on privacy (https://unity3d.com/legal/privacy-policy), which in particular includes this section:

I play a game that was built with or uses certain Unity software, what should I know?

Unity has collected some or all of the following information about your device: unique device identifiers (e.g., IDFV for iOS devices and Android ID for Android devices); IP address; country of install (mapped from IP address); device manufacturer and model platform type (iOS, Android, Mac, Windows, etc.) and the operating system and version running on your system or device; language; CPU information such as model, the number of CPUs present, frequency, and instruction set support flags; the graphics card type and vendor name; graphics card driver name and version (e.g., "nv4disp.dll 6.10.93.71"); which graphics API is in use (e.g., "OpenGL 2.1" or "Direct3D 9.0c"); amount of system and video RAM present; current screen resolution; version of the Unity Editor used to create the game; sensor flags (e.g., device support for gyroscope, touch pressure or accelerometer); application or bundle identification ("app ID") of the game installed; unique advertising identifiers provided for iOS and Android devices (e.g., IDFA or Android Ad ID); and a checksum of all the data that gets sent to verify that it transmitted correctly.

In order to play BVOVB you must consent to Unity’s privacy policy which may be updated from time to time. You can block BVOVB executable on firewall to disable any network traffic and data gathering but it will also prevent Steam achievement synchronization.