You, as Mason, are practically going through memory lane. Hopefully you remember for the last moment, the real Castro and Dragovich in front of a ship in Cuba. Anyway as a spoiler, if you played Call of Duty World at War, you'll remember one of two people: Reznov.
Prison Escape[edit]
You can't really leave without knocking the guard out with a rock. Ouch! Now follow Reznov (and many other prisoners in a black-white striped clothes) to the elevator. After you reach the end of the elevator, you have to run to the left side because once the prisoners pushed the door open, you have to go behind the large mine cart as the bullets from the mounted machine gun can cut you down in a matter of minutes. Also you'll eventually get your first gun. Follow Reznov instructions in shooting Russian guards on the left and right side. Once you reach the end, you watch the explosion allowing you to go further to the next stage.
Flaming Arrows[edit]
Now aim at the building Reznov shows you as you follow him. Go up where the poor men gets shot. So get the weapon and try to fix the trajectory for all four targets. Then go down to pick up the shotgun. It's not over as the helicopters in the air further up ahead. Get to the building, go up and use the rocket to knock the helicopter down.
Machine Gun Fury[edit]
You'll be aiming at a large building to retrieve an absurdly powerful machine gun. As you go through, the big guy dies by the electronic door. So open the door and get upstairs and continue shooting. Follow Reznov as he gets the flame thrower. Take the guards out as you go back to where the safe is. Defend him until he opens the safe. You might encounter a powerful guard with a shotgun coming to you. Once it's open get the large machine gun. Follow Reznov out into the open to cause mayhem and destroy jeeps along the way until you get knocked by gas.
Motorcycle Madness[edit]
You wake up to two motorcycles with Reznov sitting at one. It can be a tough journey the first time you play. You might crash if you don't get the handle with the motorcycle. Anyway, as you drive, use the shotgun to knock those bikers down and to move out of the way, so the enemies don't slow you down. You'll eventually reach a truck with a machine gun in the back. Cool! So if you're fast enough, get on it and shoot as many as you can. The last part when you reach it is a train and you have to jump on it. Reznov escapes on the truck and that ends your mission.