Full list of all 12 Call of Duty Classic achievements worth 200 gamerscore. It takes around 15-20 hours to unlock all of the achievements on Xbox 360.
Complete a mission using only a pistol and no melee attacks.
Complete the game on the hardest difficulty.
Complete the game.
Finish Berlin.
Finish Rocket.
Finish Hurtgen.
Complete a mission without dying or loading a checkpoint.
Complete the Russian missions.
Complete the British missions.
Complete the American missions.
Get kills using a pistol, rifle, submachine gun, and grenade in a mission without dying.
Complete Training.