In the campaign you play as two soldiers in two different companies. Sergeant Soap MacTavish in the SAS, and Sergeant Paul Jackson in the USMC. They start off on separate paths but later their stories intertwine with each other. The campaign is single player only which is stretched out across 21 missions. A few of the missions aren’t exactly missions but cut scenes. There are 4 difficulty settings in the campaign. Easy, Normal, Hardened, and Veteran. You have infinite regenerative health. It regenerates when you take cover and don’t get shot for some time. You have a set equipment set up, but you can pick up more ammo if you find the same gun or same ammo type from another gun. There are some missions with extra special grenades and other equipment.
Here is a playlist of all Call of Duty 4 missions on Veteran difficulty.
F.N.G.- Prepare for the cargo ship operation.
Crew Expendable – Infiltrate the cargo ship. Locate the ‘package.’
The Coup – The coup d’etat. Al-Asad takes over.
Blackout – Work with the ‘good’ Russians to rescue your informant,
Charlie Don’t Surf – Search for Al-Asad
The Bog – Break through the enemy lines to find the stranded
Hunted – Shot down in Western Russian with Nikolai, evade enemy
Death From Above – Protect Captain Price and the SAS using an
War Pig – Escort the Abrams back to the highway.
Shock and Awe – Surround the last of Al-Asad’s forces in the capital.
Aftermath – …
Safehouse – Final Al-Asad in his safe house in Azerbaijan.
All Ghillied Up – Crawl through Chernobyl in a ghillie suit
One Shot, One Kill – Snipe Zakhaev and escape from Chernobyl.
Heat – Defend the village of Al-Asad’s safe house while waiting
The Sins of the Father – Ambush Zakhaev’s son.
Ultimatum – Find Ssgt Griggs. Kill the power to the ICBM launch
All In – Get inside the ICBM launch facility.
No Fighting in the War Room – Reach the control room and abort
Game Over – Get the hell out of there!
Mile High Club – ???
A new mode in the game is the arcade mode. The arcade mode is unlocked after you beat the game. In this you can choose from “Full Challenge” or “Level Challenge” and play the campaign levels or the full campaign and earn points. These points will be added up at the end of each level (or if you run out of time/lives) and be displayed on the leader boards to compete against other people around the world. Depending on where you shoot the enemy, you are given points. Multiples of 5 in the range of 5 to 100 points. Grenades give you a certain amount of points, as do grenade launchers and knives. If you go on a kill streak within a certain amount of time from each kill then you get a multiplayer. X2-X8. Once you reach X8 then the music changes and you have a certain amount of time before the kill streak resets. You also get points for blowing up cars or certain objectives. At the end of the level the game adds in your time remaining along with the number of lives you earned in that level. You have a set amount of lives and can get more if you kill more enemies and reach a checkpoint. You also get a multiplier on the final score depending on the difficulty. X1.5 for normal, X3 for Hardened, and X4 for Veteran. If you go through an entire level on the Hardened and Veteran difficulties then you get an extra X2 multiplayer before the difficulty multiplier.