Full Health
Press the Tilde or key under Esc to open the console window. Now type (case-sensitive) JeffersonDarcy.
Inivisibility
Press the Tilde or key under Esc to open the console window. Now type (case-sensitive) AceEvans.
Artillery Fire
Press the Tilde or key under Esc to open the console window. Now type (case-sensitive) RogerPhilips.
Inifnite Ammo
Press the Tilde or key under Esc to open the console window. Now type (case-sensitive) StanGable.
Ammo Reload
This is different then unlimited ammo, this cheat just restores your ammo supply. Push the ~ key and type in ClayburnFallmont, this is case sensitive.