Note: Game data is stored alongside the exe, so you should move ClassiCube out of your downloads folder.
Works on OSX 10.5 and later versions.
You will need to double click ClassiCube.tar.gz to extract the executable file
libcurl and libopenal are required. You may need to install these via your package manager.
You should be able to extract the executable file by right clicking ClassiCube.tar.gz > Extract here
If that does not work, type this into terminal: tar -xvf ClassiCube.tar.gz