The second stage of the game is a shooter stage. If you are playing Game A of the American version, or Game B of the Japanese version, you must use a Zapper plugged into the second player controller port of your system. If you are playing Game B of the American version, or Game A of the Japanese version, you control an on-screen cross-hair with 
, and you shoot by pressing or holding 
or 
. The look of the cross-hairs is a little different between the versions. Other than this, and the fact that you only start out with 100 bullets in the American version compared to 150 bullets in the Japanese version, the stages are identical. The screen scrolls to the right automatically, stopping momentarily at a few locations, before continuing on with the stage.
During this stage, you are besieged by Gordon's men. They run in from the sides of the screen as well as drop down from the top of the screen. They will run around quite a bit before holding still and attacking you. Some attack with guns, and they will cause damage instantaneously. Others lob sticks of dynamite or fire rocket launches at you. These objects can be shot out of the sky before they damage you. You will lose a life if either your health meter runs out of bars, or you run out of ammunition. Extra ammunition can be obtained, but only from a few enemies. In the Japanese version, shooting the bullet item adds 50 bullets to your ammunition, but in the American version, it only adds 40. Note that you only lose a bullet of ammunition if you miss a target. If you hit a target, your current ammunition will not decrease. You will also keep all of your ammunition for the duration of the hourglass power-up.
Throughout the stage, be on the lookout for some men who are squatting behind a tree truck, or some other object in the background. These men are a bit harder to hit, but they always leave behind items. In addition to the ammunition and hourglass items mentioned above, you might also find a medical kit which replenishes all of your health, a bullet-proof vest which makes you invulnerable to enemy attack for a limited time, and a star which instantly defeats all on-screen enemies when you shoot it. It's also possible to discover an extra life if you shoot the screen in the right location, or if you shoot a star when that location is visible. Be sure to shoot these items quickly, as they disappear from the screen if they are not collected in time.
In general, a safe strategy is to keep the cross-hairs in the center of the lower half of the screen. Move left or right as necessary, but keep the vertical movement of the cross-hairs to a minimum. It does not matter if you shoot the enemy in the head or in the foot; a kill is a kill. Keeping the cross-hairs in the middle of the ground will allow you to maximize the number of enemies you can hit without adjusting the height of your aim too frequently.
Boss[edit]
Eventually, the scrolling will stop, and a blue helicopter will appear on the screen. The helicopter will sway to the left and right, back and forth across the screen. As it flies by, it will attempt to shoot you. It will also deposit a gunman on the screen if one is not already present. You're goal should be to shoot the helicopter until it is destroyed, but don't ignore the gunmen, as they will do quite a bit of damage to you if you do not eliminate them as well. Get a feel for the rhythm of the helicopter, and move your cross-hairs across the screen with the helicopter, holding the fire button down so that you can hit the helicopter more rapidly with your bullets. Eventually, the helicopter's health bar will start to dwindle. The helicopter will explode once you reduce the meter to nothing, and you will advance to the next stage.