I personally would do both of them. It mostly just depends on if you are more of a casual gamer or more of a hardcore gamer. Steam would be much better for hardcore gaming, as there are more FPS games and also more ways to play multiplayer. Really though, if you are wanting to do hardcore gaming, I would just get a PC. I know I know, I am recommending a PC on this forum, and I am not saying Macs aren't good for gaming, because they really are. They just don't have near as many games to choose from. I would personally just look at the steam website and see if there are any Mac games you would want. Good luck!