Dead Space Extraction Cheats for Wii
During gameplay you cannot change weapons except by picking up new ones but what you can do to switch weapons is access the 'Weapon' select screen, quit gameplay to the 'Main' menu then resume the level. If you do this you will only have the default amount of ammunition for the selected weapon and will lose your previous stock. You will only be able to choose one weapon and will lose the other two special weapons.
When you complete Chapter 10 'Secrets & Salvation' the 'Expert' and 'Impossible' difficulty modes become available options in Story mode.
This is done at the 'Title' screen by pressing Down, Up, Left, Right, Right, Left. If you entered the code in correctly you will hear a confirmation sound.