Easily one of the most innovative and unique things I’ve played in years. Not even really a game, it’s just an awesome interactive experience. So meta. It’s only about 6 or 7 minutes long each time you play, but wow, those minutes are pure gold. There are multiple “endings”, so keep trying again to see what the balls else may happen. It’s well worth it.
This is an exceptionally well-produced mod for Half-Life 2, so just download it and install it to your Steam mods folder and you’re ready to go. It will download the files needed to play it if you’re on a PC, you don’t need the full HL2 game installed. I think you do on a Mac though.