Max Lives Cheat: The only way to make an impossible game a little less impossible.
Max Lives Cheat
At the very beginning of the first level you'll see a red sports car. Do not destroy the car, jump over it instead. Face right and start shooting your machine gun. Keep firing at the endless stream of enemies until you max out your extra lives at 29.
Max Lives Cheat #2
In level 3, shoot the first weapon blimp to obtain the Flamethrower. Work your way to the section with the power lines and the giant mosquitoes. Pull out the Flamethrower and toast as many bugs as you need to to earn 29 lives.
Max Lives Cheat #3
You can earn 29 lives a second time on level 3 directly after climbing the building. When the helicopter appears, stand all the way to the left and equip the Machine Gun. Continue firing at the winged mutants that jump out of the helicopter until you max out your lives.