The first three games in the Call of Duty series are set in World War II. You play through the different campaigns that happened in WWII. For example in the original game for the PC you start at D-Day, storming the beaches of Normandy. In Call of Duty: World at War you are on the other side of the world in the Pacific theatre and Eastern Front.
Single Player
The single player helped evolve first person shooters from going to room to room and clearing out all the bad guys and then looking for the key or next area to go to. In Call of Duty you are with a squad of npcs who assist you in your objectives. Plus objectives can change mid mission. Objectives can range from taking down a target, to securing an area, to freeing a fallen comrade and helping him escape.
Multiplayer
The multiplayer aspects of this series have elevated the standard for first person shooters with health regeneration, kill-cam, and many different modes.
In many games before Call of Duty when a player was low on health they would have to either look for a health pack on the ground or use a limited number of charges on a self heal. Thankfully CoD changed this approach and after taking damage, a player has to wait a few seconds and their health will go back up to full, but if they continue to take damage they will die.
Another one of my favorite additions to multiplayer is the kill-cam. This shows a player how they were killed by an opponent. This sounds simple but it is very useful for locating hard to find campers. I always hated it in games when I would die over and over again to the same player because I couldn’t find their camping spot. This can also show players good places to hide themselves.
There are many different multiplayer modes, some of my favorites include; headquarters, domination, free for all, and classic team death match. Even though this series is nearing over a decade old each installment continues to add enjoyable games.