The download for the Global Defense Open Beta 1.1 Also includes directions.
Hello, dear friend! Are you ready for battle against your friend? I'm betting so! Just set up a server, invite some friends, put it on the server browser, and have an epic battle! Have fun! And remember, Global Defense is free-to-play.... forever! You just need the Source SDK Base 2007, and Steam. That's all there is to it!
So, Global Defense Open Beta 1.1 is now open to the public, complete with voice chat, new features, and a zombie spawner! Also, we're making a SERVER for Global Defense! You can too, with the Source Dedicated Server (http://www.srcds.com) and play with a friend! Stay tuned for more updates, and like the awesome trailer!