The first Valve game I ever bought was half-life. I started playing it and like a good but I couldn't stop. I thought about it all the time until I started playing again from where I left off. I told all my friends about it. They all ended up buying it eventually. It just continues from there... HL2, Ep 1, Ep 2, Team Fortress classic, TF2, Left for Dead, LFD 2, and of course my college years playing counter-strike. Love thier games and really looking forward to what will come out next!