Unity

I'm sure (in 99%) - Yes

Fervi

I just want to clarify that there are two well-known software packages called "Unity", and only one of them is libre.

The one that is libre is the desktop environment developed by Canonical and used by default in Ubuntu -- though do note that it is a rare case of libre malware by default (you need to turn off automatic sending of searches to Canonical for it to not be spyware).

The other software package called "Unity", or alternatively "Unity3D", is a game engine and IDE developed by Unity Technologies. This software package is proprietary, plain and simple.

Thank you very much guys!! I was interested in Unity (the desktop environment). I was really confused from a video that Richard Stallman talks about Ubuntu and the malware feature of Unity. You helped me a lot!!

Unity (the desktop environment) is available under the GPLv3. Contributors have to sign a CLA in order to get their stuff merged in upstream (Canonical).