Download the ZIP containing the project. Unpack the ZIP archive somewhere on your Hard Drive.
Start Unity using it's shortcut. Since Unity 5, the launcher window contains your projects. Click Open Other white button on your upper right.
Navigate and select the root folder of the project. There isn't a single file which represents the project file, but instead you must select the correct folder. The Select Folder button will light up to let you know you've selected the right folder, which should contain:
- [Project folder]
- Assets
- ProjectSettings
- .sln code solution
- [other stuff]
Once you have added the project, select it to open it up in Unity Editor. First opening of the project should take a minute or so while all assets are properly imported and added.
Simply click Play to try out the small sample level. You can control your player avatar using WASD keys to move, Shift to sprint, and E to use objects.
You can use the colored cubes in the level to change your stats. You can use the door in the level to transition scenes.
You are free to download, change, modify, copy and share the contents of this project to your hearts content. You are free to use this project or any of it's parts for any purpose whatsoever, commercial and non-commercial. You don't have to, but I'd be glad if you mentioned me if you use any of my code or assets in your project.
This project uses assets from the free "3rd Person Controller + Fly Mode" example by Vinicius Marques: https://www.assetstore.unity3d.com/en/#!/content/28647