YOU MUST OWN A SOURCE GAME THAT YOU HAVE BOUGHT OR SOMEONE HAS BOUGHT FOR YOU FOR THIS TO WORK! THE F2P VERSION OF TEAM FORTRESS 2 DOES NOT COUNT AND WILL NOT WORK!

To have the most compatible items with the game, you need to have all the games from the orange box, CS:S, Day of Defeat: Source.
Portal 2 will most likely not work with the game. Do not enter thinking it will work unless you really want to and are ready to toss out however much CS:S is right now.

You must own one of the games above (barring TF2 if you only got it when it went F2P) to make the game work properly.

Please do not spam the chat below with THANKS or I HOPE I WIN because I really don't care. I want it to be used to answer questions if people have them.