I've been using this tool for a while now to play games online with friends, and I thought I would share.
Tunngle is a free utility that allows you to play multiplayer games in LAN mode over the Internet. You and your friends join a network or room in Tunngle, and then you can play games as if you were together in a local network.
The main advantage of Tunngle is its ease of use. Instead of fiddling around with port forwarding on your router, which everyone knows can be finnicky, you just install Tunngle, join, and you're done. Pick someone to host the game server, everyone else grabs the host's IP address (from within Tunngle) and joins the server. Just as if you were together at a LAN party.
A minor annoyance is that you have to create an account, but at least it makes it easier to tell who your friends are. Also, the program oddly has sound effects. I can understand having a start-up noise, and a "dialing in" noise...sure. But a noise for each keystroke in the chat box? Really? (Thankfully they can be turned off).
Of course, the important question: does it work?
Yes, most of the time. For almost all games, it works perfectly. I have had some problems with a few games, but the problem could very well be with the game itself and not with Tunngle. Either way, I find it works much better than Hamachi, a similar tool which I used to use quite frequently but now seems to have problems with many games.
So let's say you've been looking at all these free LAN games and want to play them, but you and your friends are having trouble scheduling a LAN party. Well, even though you may not get the full LAN Party experience, you can still play multiplayer games together online with Tunngle. It's almost just as good!
Here's a link to the download page. Unfortunately, it's a Windows-only tool. :-(