Multiplayer is Alive! [Openspy Tutorial]
So, basically I used to play the absolute heck out of Arma 2: Free and me and some veteran chad tried to get it to work under a gamespy replacement called openspy with no luck.

Feeling dejected, I thought "f-ck it what about the game before Arma 2/Arma 2: Free?"
Basically here is what you do.

1.) Download a hex editior called hxd
2.) Install the hxd hex editior.
3.) Open the hxd hex editor.
4.) Drag and drop the Arma executable into the hxd window.
5.) Press Ctrl+R
6.) Search for gamespy.com and replace all with openspy.net
7.) Click the save icon and repeat steps 1-6 with the arma server executable.

You should be able to run the game with working multiplayer.
Enjoy.