Just a thought, but why not ask on their forums, or in fact a store which actually has those games?

I asked there, but got nothing :(

Why do you need specific friends to play them? Aren't there some public servers where you just join and start shooting each other in the ass?

I've played Team Fortress series games for many many maaaaaany years, without any real-life friends to play with. I just hop in to some public server, kill everyone, and happily hop out. I don't feel like I need to know anyone else in the server to play with them, maybe it is even better I don't so I can swear openly and call them all dildos.

A few times I've played TF2 together with a real-life friend, joining the same public server with him. Ok it did give some advantage when we were playing side by side on our laptops and I could ask him to cover my ass and vice versa, but he usually got bored doing that and wandered off right away, so I could have played without him just as well. With friends like these...