This project follows along with Unity 5: 2D Building an Adventure Game with Jesse Freeman Link: https://www.lynda.com/Unity-2D-tutorials/Unity-5-2D-Building-Adventure-Game/513588-2.html
The strategy given for packing sprites is outdated as of Unity 2017. This method may still be supported by the Legacy Sprite Packer (enable via project settings), but the newer method uses Sprite Atlases to provide packing instead.
See: https://docs.unity3d.com/2017.1/Documentation/Manual/SpriteAtlas.html