James Pond: Robocod Cheats :
Secret - Limited Invincibility
At The beginning of the game outside the factory, there will be a number of items located on the roof. If you get them in this order (Cake, Hammer, Earth, Apple, Tap) You will get Invincilbility for a limited time (This spells out CHEAT). This is a holdover from the original Mgadrive version, but in that game it was 20 minutes.