Thank you SnipeaxX, I know how logmein-hamachi works.

With or without hamachi or other VPN service, the multiplayer mode requires a high bandwidth (understand HIGH SPEED INTERNET CONNECTION). So for me, with just 4mbps aDSL connection, it is not possible to play with a friend. With two or three ships on the "level", it is ok, but one more ship (with many AI controlled units), and the game become unplayable. And we are only two on the server...

I think the game needs more network optimizations.