I assume I need to use something like Hamachi. Just using my public IP doesn't work and in game it displays the local IP from my router.

Has anyone succesfully joined/hosted a game? If so can you please explain how. Thanks.

Ditto. I'm having the same problem. On a fresh install I was able to connect to another computer, but after that nothing. I have 2 Win7 and a Win8 machines I'm trying to get multiplayer to work on LAN.