Open Level Cheats

Enter these cheats while in the folder menu.  They can be used to open up levels!  But you can only open up the next level, so you have to use the codes in order toget them all.
 
Open the Dam (only if it is the first level you haven't completed)
L+R+C up
R+D left
R+C down
L+C down
R+D up
L+D down
R+C right
L+D right
L+R+D right
R+C down

Open facility level (enter at mission select screen, only works if
facility is the first 'locked' level)
L+R+C up
R+C left
L+D left
R+C up
L+D left
R+C down
L+C right
R+D right
L+R+C up
L+D right

Open runway
L+R+D left
R+D left
L+C up
L+D left
R+C up
R+C down
R+C right
R+D right
L+D down
R+C left

Open surface 1
R+C left
L+R+C up
L+D left
R+D up
R+D left
L+D up
R+C down
L+D right
L+C right
L+R+D down

Open bunker 1
L+C down
R+D right
L+C right
R+C left
L+C down
L+R+D left
L+C right
L+R+D up
R+C right
L+D up

Open silo
L+D up
R+C down
L+D left
R+D down
L+C left
L+R+C right
L+C up
R+D right
R+D right
R+C right

Open frigate
R+C up
L+D down
R+C right
L+D left
L+R+D up
L+R+C down
R+C right
R+D up
L+R+C down
R+D up

Open silo
L+D left
L+R+D right
L+C left
R+D right
L+C up
L+D left
L+C down

Open statue
L+R+C down
L+R+C down
L+D right
L+R+D left
R+D left
R+C right
L+R+D left
R+C up
R+C down
R+D right
 

Open archives
R+D left
L+R+D up
L+R+C down
R+D left
L+R+C right
L+D left
L+R+D right
L+R+C down
L+D up
R+C down

Open streets
L+R+C left
L+C right
L+D up
L+R+C down
R+C right
R+C down
R+D left
R+C down
R+C up
L+D down

Open depot
L+D down
L+D down
R+C down
L+C right
L+R+D right
R+C left
L+D down
L+C left
L+C right
L+D up

Open train
R+D left
R+C down
R+C right
L+R+D left
L+D right
R+C down
L+D left
L+R+C left
L+D up
L+C up

Open jungle
R+C down
R+D left
L+R+D up
R+D right
R+D down
R+D down
R+D up
R+C left
R+C up
L+R+D left

Open control
L+C down
R+D down
L+D right
R+C right
R+C down
R+D left
R+D left
R+C up
R+D left
L+R+C up

Open caverns
L+D down
R+C down
L+R+D up
L+D right
R+C up
R+C left
R+D up
L+C left
L+D up
R+C left

Open cradle
L+R+C up
L+D left
R+D down
L+D down
L+C up
L+D down
R+D right
R+C up
L+C left
R+D right

Complete cradle on agent, give magnum cheat
R+C down
R+D left
L+D right
L+R+C right
L+D down
L+R+C up
L+D left
L+R+C up
L+R+D right
L+C left