Topic title says it all. I also need Operation Arrowhead, right? I'm thinking of buying that so I can run the mod (surprising because I'm actually saving up for something else, but this is too interesting to pass up!) Is it possible for me to run the mod with the free original game and the expansion? Also, is Steam required?

I'm into zombie games, if that's any good. I really just want to experience the game, and how bad are we talking about the free version?

It's alright. I'm not really in it for the HD textures (considering one, I'm still saving up and two, I'm playing on a laptop and it might lag too much on me.) Glad I can use the free version; now I just need to find out where to buy OA. Are physical copies available in stores?