It seems that you're using an outdated browser. Some things may not work as they should (or don't work at all).
We suggest you upgrade newer and better browser like: Chrome, Firefox, Internet Explorer or Opera

×
I just bought the gog.com version of this game and I decided I want to play this with my friend who has it on cd.

We have some problems making connections however.

When I start up the game multiplayer it tells me my cd key is invalid.

I also tried setting up LAN via. hamachi but that doesn't seem to work either.

Does anyone have an idea on how to play this online?
This question / problem has been solved by LaithArkhamimage
You have to request a unique CD key from GOG in order to play some games (such as this one) over multiplayer.

To do this, go to the Support section at the top, click Contact Us, select the Other option on the page, and in the message say you're requesting a CD key for this game. They should email you a key within a few days.