title: how to install unity3d on ubuntu 15.10
body: <p>I download unity 3D games editor from <a href="http://www.omgubuntu.co.uk/2015/08/unity3d-linux-build" rel="nofollow noreferrer">omg ubuntu</a>
  but when i install it, the ubuntu software center give me an eror:</p>
  
  <p><img src="https://i.stack.imgur.com/JubwS.png" alt="enter image description here"></p>
  
  <p>What should i do?</p>