Downloading the Repo as a Zip file won't work (because some bigger files will be a small txt file instead of the actual file). You should use a Git client. Github Desktop is the easiest to use, here's a link: https://desktop.github.com/

Once it's installed, go to File > Clone Repository and paste the URL of this repository in.

Updates are pushed semi regularly, so find out how to keep the repo up to date (Fetch Origin, or Repository > Pull).

We're on Unity 2018.2 - download it here: https://unity3d.com/get-unity/update

Open the project. You can see the demo maps in Assets/Missions/Demos. Open Demo Buttons.

You should see something like this

You should be able to choose Open In Game to test the map in game.

It'll ask you to find the Tub.exe, then bundle the map up and let you play. The first time you bundle a map up will take a lot longer than subsequent times.

Tub Forums: https://forum.facepunch.com/f/tub/

Discord: https://discord.gg/N4QtNeJ

You can do whatever you want with the code in this repository. Use it, change it, sell it, we don't care. By code we mean all .cs and all .shader files.

The other assets, the art and content, you shouldn't use those in your own game. The exception to this is any textures or materials you need to make a .shader work - feel free to take and reuse those.