Call of Duty 4 is an excellent first-person shooter. This is one of the first major commercial games to be ported to the Mac OS X operating system. It was ported by Aspyr, and they have done a great job of keeping the great experience that Call of Duty: Modern Warfare was for me when I first played it. Installation is also much easier on the Mac than on Windows. To install the game, you simply have to move the game folder from the DVD to a folder on your disk, and off you go.
Call of Duty 4 for Mac comes with two executable files, one of the single player campaign and another for the multiplayer component. The single player campaign is excellent in so many different ways. I still remember when I first played it and how amazed I was at the graphical details and the cut-scenes. It all looks so realistic, and playing this game is like getting yourself into a movie. The following games on the franchise (except for World at War) follow the events of this game. So you have to play it before you play Modern Warfare 2.
Although I've read of some people having problems with this game on the Mac, I didn't experience any. The experience was smooth for me from installation to playing.