Beat No Russian on any difficulty and select it a second time. Choose Veteran this time and, when the level starts, choose to skip it. The level will be marked as complete.

Complete the Ghillie in the Mist challenge to unlock different camos (ghillie suits) for use with your sniper classes:

    * Artic camo
    * - Get 50 one-shot kills with sniper rifles Urban camo
    * - Get 100 one-shot kills with sniper rifles Desert camo
      - Get 200 one-shot kills with sniper rifles

Reach level 70 in multiplayer and enter Prestige Mode to unlock an additional custom class slot for a total of six.

The following weapons and equipment can be unlocked by attaining the (multiplayer) levels below:

      Assault Rifles
    * FAMAS - Lvl. 1
    * M4A1 Carbine - Lvl. 4
    * SCAR-H - Lvl. 8
    * TAR-21 - Lvl. 20
    * FAL - Lvl. 28
    * M16A4 - Lvl. 40
    * ACR - Lvl. 48
    * F2000 - Lvl. 60
    * AK-47 - Lvl. 70
    * M14 EBR - Campaign Only
    * G3 - Campaign Only

      Submachine Guns
    * UMP .45 - Lvl. 1
    * MP5k - Lvl. 4
    * Vector - Lvl. 12
    * P90 - Lvl. 24
    * Mini Uzi - Lvl. 44

      Light Machine Guns
    * L86 LSW - Lvl. 1
    * RPD - Lvl. 4
    * MG4 - Lvl. 16
    * AUG HBAR - Lvl. 32
    * M240 - Lvl. 52

      Sniper Rifles
    * CheyTac Intervention - Lvl. 1
    * Barrett .50 Cal (AKA M107) - Lvl. 4
    * WA2000 - Lvl. 36
    * M21 EBR - Lvl. 56
    * Dragunov - Campaign Only

      Secondary Weapons
    * PP-2000 - Machine Pistols Lvl. 1
    * Glock 18 - Lvl. 22
    * M93 Raffica - Lvl. 38
    * TMP - Lvl. 58

      Shotguns
    * SPAS-12 - Lvl. 1
    * AA-12 - Lvl. 12
    * Striker - Lvl. 34
    * Ranger - Lvl. 42
    * M1014 - Lvl. 54
    * Winchester 1887 - Lvl. 67
    * W1200 - Campaign Only

      Handguns
    * USP .45 - Handguns Lvl. 1
    * .44 Magnum aka Colt Anaconda - Lvl. 26
    * M9 - Lvl. 46
    * Desert Eagle - Lvl. 62
    * M1911 - Campaign Only

      Launchers
    * AT4-HS - Lvl. 1
    * Thumper x2 aka M79 grenade launcher - Lvl. 14
    * Stinger - Lvl. 30
    * Javelin - Lvl. 50
    * RPG-7 x2 - Lvl. 65

      Other
    * Frag Grenade - Lvl. 1
    * Semtex - Lvl. 1
    * Throwing Knife - Lvl. 7
    * Tactical Insertion - Lvl. 11
    * Blast Shield - Lvl. 19
    * Claymores - Lvl. 31
    * C4 - Lvl. 43
    * Knife
    * Ice Picks
    * Smoke grenade
    * Stun grenade

      Attachments
    * Red Dot Sight
    * EOTech Holographic Weapon Sight
    * MARS Sight
    * ACOG Sight (and various telescopic sights that are specific to certain guns)
    * Thermal Scope
    * Suppressor
    * Grenade Launcher
    * Heartbeat Sensor
    * Shotgun
    * Extended Magazine
    * Full Metal Jacket ammunition (replacement for Deep Impact)
    * Sniper Scope (will not take up an attachment slot, just like in Call of Duty 4)
    * Akimbo
    * Rapid Fire (replacement for Double Tap)
    * Foregrip
    * Tactical Knife

Complete the campaign on any difficulty to unlock the museum. In each of the exhibit halls with character models, pressing the red button (which helpfully displays "Do NOT Press ...") will immediately bring the characters to life and they will immediately attempt to kill you.

You can unlock the following rewards by meeting the Killstreak requirements below:
.

    * 3 - UAV (Reveals enemies on minimap)
    * 4 - Care Package (ammo / killstreak air drop -- can be collected by anyone)
    * 4 - Counter UAV (disable enemy maps)
    * 5 - Sentry Gun (airdropped)
    * 5 - Predator (directed missile)
    * 6 - Precision Airstrike (choose a location to bomb)
    * 7 - Harrier Strike (choose a location to bomb and defend with a Harrier)
    * 7 - Attack Helicopter (helicopter backup)
    * 8 - Emergency Airdrop (four ammo / killstreak air drops -- can be collected by anyone)
    * 9 - Pave Low (armored helicopter backup)
    * 11 - Chopper Gunner (operate a helicopter gun)
    * 11 - AC130 (operate a plane gun)
    * 15 - EMP (disable enemy electronics)
    * 25 - Nuclear Strike (kills all members of both teams)