Infinate Stealth Tanks
you can get infinate stealth with the stealth tanks When using a unit with the ability of stealth, turn it on and then wait for the percentage to reach 1% then turn it off and turn it on again. You'll notice that it starts counting into the negative numbers as high as you could imagine. Once the unit dies you MUST redo the trick.
Level 15 Password
NORAD
Triangle/square/triangle
circle/X/square
circle/circle/square
WOPR
circle/square/circle
X/square/X
triangle/circle/X