As I had not played one in a long time, I found myself recently wanting to give an FPS a whirl. Without my gaming computer with me, I had to download something that would not occupy too much space. So, I decided on the Call of Duty Single Player Demo. This is a demo of Call of Duty 4: Modern Warfare from Infinity Ward. I was a big fan of the original, so it was a natural choice for me.
What I found was that the gameplay, graphics, sound, and control are all intact, despite a very small file size. However, I found it would not install without administrative priveleges, which was an annoyance. Once installed, I found one mission was included, "Bog" from the full game. The objective is to buy time for engineers to repair a stalled Abrams tank behind enemy lines in the Middle East. Personally, I'd have chosen a mission with a little more action for the player.
Though it doesn't last long and requires a full installation, it does give a solid taste of what COD4 has to offer. If you are unfamiliar with this franchise, it's not a bad place to start looking!