First of all, you and your friend(s) need to install a client called hamachi. Link for download- (https://secure.logmein.com/products/hamachi/download.aspx) Download the unmanaged version. You both might need to make accounts. Power on hamachi by clicking the power button if it's a gray color. Next one of you needs to create a network. Click the network tab and click create network. Create a network and write down your chosen password and network name. All your friends need to join the network by going to the same network tab but click join instead. Once they have joined they should see your network. They need to right click your name and select "Copy ip4 address". All you need to do now is start a new game and select "2 players" at the map selection screne. You are done. All the friends that are in the group need to join now. Do not just click join game or invite them. They need to open console.(If you don't know how, scroll down) Once open type connect . After connect, paste the address into the box. Then click submit. Done.
If this method worked, please tell me.


*If you don't know how to open console*
At the main menu, click options. On the bottom of the menu, there is a button that says advanced options. Click it. Check the box that says developers console. With the menu still open, press the squigly line ( ~ ) right below the Esc key. You now have the console open.