Once the act's theme starts to be heard of from the Yamaha YM-2151, the screen will start scrolling inward, as it crashes through a pair of double doors; once the explosion has cleared, you will come to a barrage of twelve Zaku (the first three of whom are on that balcony in the background), who are firing shots at you. Once you have fired one shot at each of them to kill them, the screen will start scrolling to the right as a thirteenth Zaku and two Tarantulas come running into view from the left and right sides of the screen, while firing shots at you - and once you have fired enough shots at each of them to kill them, two more Zaku will drop down to the ground from the top of the screen, and start firing shots at you. Once you have fired a shot at both of these to kill them, a sixteenth Zaku will slide down into view from the top of the screen on a pole in the background and start firing shots at you; once you've fired a shot at him to kill him, five more Zaku will come running into view from the left and right sides of the screen, while firing shots at you. Once you've fired a shot at each of them to kill them, a twenty-second Zaku will jump out of a manhole, and start firing shots at you - and once you have fired a shot at him to kill him, a twenty-third Zaku will come up from behind a stack of two crates in the background and throw a grenade at you. Once you have fired a shot at him to kill him a twenty-fourth Zaku will slide down into view from the top of the screen on another pole in the background and start firing shots at you; once you fire a shot at him to kill him, three Domu will come running into view from the right side of the screen (again, on that aforementioned balcony in the background) and start firing missiles at you. Once you've fired enough shots at each of them to kill them a twenty-sixth Zaku will jump out of another manhole, and start firing shots at you - and once you've fired a shot at him to kill him, three more Zaku will come running into view from the left and right sides of the screen, while firing shots at you. Once you have fired a shot at each of these, to kill them, an Innocent Bystander will come running into view from the right side of the screen as the text "DON'T SHOOT" appears above him; a third Tarantula will then come running into view from the right side of the screen while firing shots at you. Once you have fired enough shots at him to kill him, a fourth Tarantula will come running into view directly in front of you from the left side of the screen and start firing shots at you - and once you've fired enough shots at him to kill him, three more Zaku will emerge from the first, second and third holes in the wall in the background, and start running directly towards you while firing shots at you. Once you have fired a shot at him to kill him, a thirty-third Zaku will jump out of a third manhole, and start firing shots at you; once you have fired a shot at him to kill him, three more Zaku will emerge from the second, third and fifth hole in the wall in the background, and start running directly towards you while firing shots at you. Once you've fired a shot at both of them to kill them, three ropes will lower three more Zaku into view from the top of the screen as they start firing shots at you - and once you've fired a shot at each of them to kill them, two more Zaku will jump out of two more manholes, then start firing shots at you. Once you've fired a shot at both of these to kill them, a fourth rope will lower a forty-second Zaku into view from the top of the screen, as he begins firing shots at you; once you have fired a shot at him to kill him, a forty-third Zaku will jump out of a sixth manhole and start firing shots at you. Once you have fired a shot at him to kill him, another Innocent Bystander will come running into view on the right side of the screen, as the text of "DON'T SHOOT" appears above him - and two more Tarantulas will then come running into view from that right side of the screen, while firing shots at you. Once you've fired enough shots at both of them to kill them, a fifth rope will lower a forty-fourth Zaku into view from the top of the screen as he starts firing shots at you; once you have fired a shot at him to kill him, five more Zaku will leap into view from the right and left sides of the screen, while firing shots at you. Once you have fired a shot at both of them to kill them, the screen will start scrolling inward again, as it comes to another pair of double doors - and once they have opened, you will come to thirty-two Atmospheric Airships on the left and right sides of the screen (which, unlike all the other ones you have encountered, will not attack)...
Once you have fired enough shots at each of these to kill them, four Kurage will come running into view from the left side of the screen, while firing shots at you; once you've fired a shot at each of these to kill them, three more Zaku will come leaping into view from the left and right sides of the screen, while firing shots at you. Once you have fired a shot at each of these, to kill them, two Airship Zaku will come flying into view from the right and left sides of the screen, while firing shots at you - and once you have fired enough shots at both of these to kill them, five more Zaku will come leaping into view from the left and right sides of the screen, while firing shots at you. Once you've fired a shot at each of them, to kill them, three more Airship Zaku will fly into view from the right and left sides of the screen, while firing shots at you; once you've fired enough shots at each of these, to kill them, four more Zaku will leap into view from the left and right sides of the screen while firing shots at you. Once you've fired a shot at each of them to kill them, four more Airship Zaku and a Mosquito will come flying into view from the left and right sides of the screen, while firing shots and missiles at you - and once you've fired enough shots at each of them, to kill them, you will come to a third pair of double doors. Once they have opened, you will come to another barrage of three more Zaku, who are firing shots at you; once you fire a shot at each of them to kill them, the screen will start scrolling downward like in the original second act.
Seven more Zaku will then come running into view from the right and left sides of the screen (on two bridges in the background) while firing shots at you; once you've fired off a shot at all of these ones, to kill them, a thirty-third Atmospheric Airship and three more Zaku will come flying and running into view from the right and left sides of the screen (the latter of whom are on a third bridge in the background), while firing missiles and shots at you. Once you've fired enough shots at each of these, to kill them, two more Atmospheric Airships, two more Domu, and three more Zaku will come flying and running into view from the right and left sides of the screen (the second and third of whom are on a fourth bridge in the background) while firing missiles and shots at you - and once you've fired enough shots at each of them to kill them, another Mosquito will come flying up into view from the bottom of the screen while firing missiles at you. Once you have fired enough shots at him to kill him, two more Domu and three more Zaku will come running into view from the left and right sides of the screen (on two more bridges in the background), while firing missiles and shots at you; once you fire enough shots at each of them to kill them, a thirty-sixth Atmospheric Airship and a tenth Airship Zaku will fly into view from the left and right sides of the screen while firing missiles and shots at you. Once you fire enough shots at both of these to kill them, a Beam Gun will emerge from the left side of the screen, to start firing shots at you - and once you've fired enough shots at it to kill it, an eighty-first Zaku will come running into view from the right side of the screen (upon a platform in the background), and start firing shots at you. Once you've fired a shot at him to kill him, an eleventh Airship Zaku will come flying into view from the left side of the screen while firing shots at you; once you have fired enough shots at him to kill him, two more Domu and two more Airship Zaku will come running and flying into view from the right side of the screen (on a seventh bridge in the background), while firing missiles and shots at you. Once you've fired off enough shots at each of them to kill them, a second Beam Gun will emerge from the left side of the screen and start firing shots at you; once you've fired enough shots at it to kill it, four more Zaku will come running into view from the left side of the screen (on an eighth bridge in the background) while firing shots at you. Once you've fired a shot at each of them to kill them a third Mosquito will come flying up into view from the bottom of the screen while firing missiles at you - and once you have fired off enough shots at him to kill him, a fourteenth Airship Zaku will come flying into view from the right side of the screen while firing shots at you. Once you have fired enough shots at him to kill him, three more Domu will come running into view from the left and right sides of the screen (on a ninth bridge in the background) while firing missiles at you; once you've fired enough shots at each of these to kill them, a third Beam Gun will emerge from the right side of the screen, and start firing shots at you. Once you have fired enough shots at it to kill it, four more Zaku will come running into view from the left and right sides of the screen (on a tenth bridge in the background) while firing shots at you - and once you've fired a shot at each of them to kill them, a ninetieth Zaku will run into view from the left side of the screen (upon another platform in the background) while firing shots at you. Once you have fired a shot at him to kill him, a third Innocent Bystander will come running into view from the right side of the screen (on an eleventh bridge in the background) as the text "DON'T SHOOT" appears above him; two more Airship Zaku will now come flying down into view from the top and right side of the screen while firing shots at you. Once you have fired enough shots at both of them to kill them, five more Zaku will come running into view from the left and right sides of the screen (on a twelfth bridge in the background) while firing shots at you - and once you've fired a shot at each of them to kill them, a seventeenth Airship Zaku will fly into view from the left side of the screen while firing shots at you. Once you've fired enough shots at him to kill him, a fourth Mosquito will come flying up into view from the bottom of the screen, while firing missiles at you; once you fire enough shots at him to kill him, four more Airship Zaku and a ninety-sixth Zaku will come flying and running into view from the left and right sides of the screen (upon two more bridges in the background), while firing shots at you. Once you have fired enough shots at each of them to kill them, a twenty-second Airship Zaku will come flying down into view from the top of the screen, while firing shots at you - and once you have fired enough shots at him, to kill him, three more Zaku will come running into view, on the right and left sides of the screen (upon a fifteenth bridge in the background), while firing shots at you. Once you have fired a shot at each of them to kill them a fifth Mosquito will come flying up into view from the bottom of the screen while firing missiles at you; once you've fired enough shots at him to kill him, a fourth Beam Gun will emerge from the right side of the screen and start firing shots at you. Once you have fired enough shots at it to kill it a 100th Zaku will run into view from the left side of the screen (on a third platform in the background) while firing shots at you - and once you have fired a shot at this one, to kill him, a fourth Innocent Bystander will come running into view from the left side of the screen (on a sixteenth bridge in the background) as the text "DON'T SHOOT" appears above him. A sixth Mosquito will then come flying up into view from the bottom of the screen, while firing missiles at you; once you've fired enough shots at him, to kill him, four more Zaku will come running into view from the left and right sides of the screen (on a seventeenth bridge in the background), while firing shots at you. Once you've fired a shot at each of them to kill them, two more Airship Zaku will come flying down into view from the top of the screen, while firing shots at you - and once you have fired enough shots at both of them to kill them, the screen will start scrolling inward once again, as it comes to a fourth pair of double doors. Once they have opened, you will come to a third barrage of four more Zaku, who are firing shots at you - and once you've fired a shot at each of these, to kill them, a 109th Zaku will emerge from the eighth hole in the wall in the background and start running directly towards you while firing shots at you. Once you have fired a shot at him to kill him, two more Zaku will jump out of two more manholes and start firing shots at you; once you have fired a shot at both of them to kill them, a 112th Zaku will come leaping into view from the right side of the screen while firing shots at you. Once you have fired off a shot at him to kill him a Ceiling Gun will come down into view from the top of the screen while firing shots at you; once you have fired a shot at it to kill it, two more Zaku will emerge from the ninth and tenth holes in the wall in the background, and start running towards you while firing shots at you. Once you have fired a shot at both of these to kill them, a 115th Zaku will come leaping into view from the left side of the screen while firing shots at you - and once you have fired a shot at him to kill him, three more Zaku will emerge from the seventh, eighth and tenth holes in the wall in the background, and start running directly towards you while firing shots at you. Once you have fired a shot at each of these to kill them, a 119th Zaku will jump out of a ninth manhole, then start firing shots at you; once you have fired a shot at him to kill him, another Ceiling Gun will come down into view from the top of the screen, while firing shots at you. Once you've fired a shot at it to kill it, two more Zaku will emerge from the seventh and ninth holes in the wall in the background and start running directly towards you while firing shots at you - and once you've fired a shot at both of them to kill them, two more Zaku will jump out of a two more manholes and start firing shots at you. Once you have fired a shot at him to kill him, two more Zaku will emerge from the eighth and ninth holes in the wall in the background, then start running directly towards you while firing shots at you; once you have fired off a shot at both of them to kill them a third Ceiling Gun will come down into view from the top of the screen while firing shots at you. Once you have fired a shot at it to kill it, the screen will start scrolling to the left, as two more Zaku emerge from the tenth and eleventh holes in the wall in the background, and start running directly towards you while firing shots at you - and once you have fired a shot at both of them to kill them, a fourth Ceiling Gun will come down into view from the top of the screen while firing shots at you. Once you have fired a shot at it to kill it, a sixth Tarantula will come running into view directly in front of you on the left side of the screen while firing shots at you; once you've fired enough shots at him to kill him, a 128th Zaku will emerge from the ninth hole in the wall in the background, then run directly towards you while firing shots at you. Once you have fired a shot at him to kill him, a fifth Ceiling Gun will come down into view from the top of the screen while firing shots at you - and once you have fired a shot at it to kill it, two more Zaku will jump out of two more manholes and start firing shots at you. Once you have fired a shot at both of them to kill them, two more Zaku will emerge from the tenth and eleventh holes in the wall in the background and start running directly towards you while firing shots at you; once you've fired a shot at both of them to kill them, a sixth Ceiling Gun will come down into view from the top of the screen while firing shots at you. Once you have fired a shot at it to kill it three more Zaku will emerge from the thirteenth, twelfth and fourteenth holes in the wall in the background and start running directly towards you while firing shots at you - and once you have fired a shot at each of these to kill them, two more Zaku will come leaping into view from the left side of the screen while firing shots at you. Once you've fired a shot at both of these to kill them, a seventh Ceiling Gun will come down into view from the top of the screen while firing shots at you; once you have fired off a shot at it to kill it three more Zaku will emerge from the tenth and eleventh holes in the wall in the background, then start running directly towards you while firing shots at you. Once you have fired a shot at each of them to kill them, a 141st Zaku will come leaping into view from the left side of the screen while firing shots at you - and once you have fired a shot at him to kill him, three more Zaku will emerge from the fifteenth, fourteenth and sixteenth holes in the wall in the background and start running directly towards you while firing shots at you. Once you have fired a shot at both of them to kill them, a seventh Tarantula will come running into view from that right side of the screen, while firing shots at you; once you've fired enough shots at him to kill him, two more Ceiling Guns will come down into view from the top of the screen while firing shots at you. Once you have fired a shot at both of them to kill them, the screen will start scrolling inward yet again as it comes to a fifth pair of double doors - and once they have opened, you will come to a third barrage of two more Zaku who are firing shots at you. Once you've fired a shot at both of them to kill them, a fifth Innocent Bystander will come running into view from the left side of the screen, as the text "DON'T SHOOT" appears above him; you'll then come to a sixth pair of double doors. Once these have opened you will come to a fourth barrage of two more Zaku who are firing shots at you - and once you have fired a shot at both of them to kill them a sixth Innocent Bystander will come running into view from the left side of the screen as the text of "DON'T SHOOT" appears above him. You'll then come to this seventh pair of double doors; once they have opened you will come to a fifth barrage of three more Zaku who are firing shots at you. Once you have fired a shot at each of them to kill them, the text "IT'S THEIR MAIN LAB! WE'VE GOTTA DESTROY EVERYTHING!" will appear on the screen - but this does not mean that it is the end of the act...
The screen will then start scrolling to the left again, as four more Zaku run into view from its right and left sides while firing shots at you; once you've fired a shot at each of them to kill them, you will come to eight Capsules. Once you've fired off a shot at each of them to destroy them, a tenth Ceiling Gun will come down into view from the top of the screen while firing shots at you; once you have fired a shot at it to kill it, a 156th Zaku and a thirteenth Domu will come leaping and running into view from the left side of the screen while firing shots and missiles at you. Once you've fired enough shots at both of them to kill them, six more Zaku will run into view on the left and right sides of the screen, while firing shots at you; once you have fired a shot at each of these to kill them, an eleventh Ceiling Gun will come down into view from the top of the screen while firing shots at you. Once you've fired a shot at this to kill it you'll come to twelve more Capsules - and once you fire a shot at each of these to destroy them, three more Tarantulas will come running into view from the left and right sides of the screen while firing shots at you. Once you've fired enough shots at each of them to kill them a twelfth Ceiling Gun will come down into view from the top of the screen while firing shots at you; once you have fired a shot at it to kill it a fourteenth Domu will come running into view from the left side of the screen while firing missiles at you. Once you have fired enough shots at him to kill him, a 163rd Zaku will come leaping into view from the left side of the screen while firing shots at you - and once you've fired a shot at him to kill him an eleventh Tarantula will come running into view from the right side of the screen, while firing shots at you. Once you've fired enough shots at him to kill him, a thirteenth Ceiling Gun will come down into view from the top of the screen while firing shots at you; once you have fired a shot at this to kill it you will come to three more Capsules. Once you have fired a shot at each of them to destroy them a twelfth Tarantula will come running into view from the left side of the screen while firing shots at you - and once you've fired enough shots at him, to kill him, a fourteenth Ceiling Gun will come down into view from the top of the screen, while firing shots at you. Once you've fired a shot at it to kill it, three more Zaku will drop down into view from the top of the screen while firing shots at you; once you have fired a shot at each of them to kill them, you will come to six more Capsules. Once you have fired a shot at each of them to kill them, a fifteenth Ceiling Gun will come down into view from the top of the screen, while firing shots at you - and once you have fired a shot at it to kill it, four more Zaku will come running into view from the right and left sides of the screen while firing shots at you. Once you have fired off a shot at each of them to kill them, two more Ceiling Guns will come down into view from the top of the screen while firing shots at you; once you've fired one shot at both of them to kill them two more Zaku and two more Tarantulas will come running into view from the left and right sides of the screen, while firing shots at you. Once you've fired enough shots at each of them to kill them, you will come to seven Clone Aliens on the right side of the screen - and once you have fired enough shots at each of them, to kill them, the screen will start scrolling inward for a fifth time, as five more Zaku come leaping into view from the left and right sides of the screen while firing shots at you. Once you have fired a shot at each of them to kill them, you will come to seven more Clone Aliens on the left side of the screen; once you have fired enough shots at each of these to kill them, you will come to an eighth pair of double doors - and once they have opened, you will come to a sixth barrage of four more Zaku who are firing shots at you. Once you have fired a shot at each of them to kill them, you will have to fire a shot at three panes of glass to destroy them, before meeting up with Vanguard and Great Leader Danbain, who will transform into two Dummies as the song you had been hearing from the Yamaha YM-2151 stops playing out, and the text "IT'S A DECOY! WE'VE BEEN TRICKED!" appears at the bottom of the screen.
Once you have fired a shot at both of the Dummies to kill them the screen will start scrolling to the left once again as rocks start falling from its top; it will then start scrolling inward for a sixth time, as it comes to a single door (the text "SHOOT" will also appear over it at this point). Once you've fired enough shots at it to destroy it, the act's second theme will start to be heard from the Yamaha YM-2151 and two more Atmospheric Airships will come flying into view from behind you while firing "energy bombs" at you - and once you've fired enough shots at it to kill it, two more Zaku will drop down into view from the top of the screen, while firing shots at you. Once you've fired a shot at both of these to kill them, four more Atmospheric Airships will come flying into view from behind you, while firing "energy bombs" at you; once you have fired off enough shots at all of these to kill them, a seventh Mosquito will come flying up into view from the bottom of the screen, while firing missiles at you. Once you've fired off enough shots at him to kill him, six more Atmospheric Airships will come flying into view from behind you while firing "energy bombs" at you - and once you've fired enough shots at each of these to kill them, two more Mosquitoes will fly up into view from the bottom of the screen while firing missiles at you. Once you fire off enough shots at both of them to kill them, the screen will scroll upward, then start scrolling inward for a seventh time, as three more Zaku, two more Airship Zaku and a fifteenth Domu drop down into view from the top of the screen (while firing shots and missiles at you); once you have fired enough shots at each of these to kill them, a ninth pair of double doors will close in front of you just before you crash through them. Once the explosion has cleared, the screen will begin scrolling inwards for an eighth time, as you come to twelve Mountains of Needles - and once you have fired a shot at each of them to kill them, four more Beam Guns will emerge from the left and right sides of the screen and start firing shots at you. Once you have fired enough shots at each of them to kill them, four more Airship Zaku will come flying into view from the left side of the screen, while firing shots at you; once you have fired enough shots at each of these to kill them, three more Atmospheric Airships will come flying into view from behind you while firing missiles at you. Once you have fired enough shots at each of them to kill them, the screen will start scrolling to the right again as three more Airship Zaku come flying into view from the left side of the screen while firing shots at you - and once you have fired enough shots at each of these to kill them, the screen will start scrolling inward for a ninth time, as two more Atmospheric Airships come flying into view from behind you, while firing missiles at you. Once you've fired enough shots at both of them to kill them, you will come to eight more Mountains of Needles; once you have fired a shot at each of these ones to kill them, you will crash through a wall as seven more Atmospheric Airships come flying into view from behind you while firing missiles at you (Vanguard's ship is also visible in the sky at this point). Once you fire enough shots at each of them to kill them, Vanguard's ship will fire a shot - and the screen will then scroll to the right once again, then scroll outward as the shot hits the island in the background and it explodes (the song you had been hearing from the Yamaha YM-2151 will also stop playing out at this point). The big blue aeroplane from the end of the two previous acts will then come in to land, and the screen will scroll inward for a tenth time as it goes into it (once again, there's no boss for this act); both players' scores (which were, yet again, not displayed during gameplay) will then be displayed at the top of the screen under those texts "1UP" and "2UP", and their hit/miss ratios on either side of that text "HIT RATE" above the shot of the unnamed Neo Arc female operative. The texts "REPAIRING DAMAGE" and "WEAPONS SUPPLY" will also be displayed below it - and the text "WE'VE BEEN WIPED OUT. IS THAT THEIR WINNING CARD?" will then appear below the shot, just before the screen goes black and cuts back to a shot of Vanguard's ship:
The text "THE CITY IS UNDER ATTACK!! NO MORE MR. NICE GUY." will then appear below the shot, and Garcia and Cliff (who, once again, have not been informed of "Today's Grievances" by the new Neo Arc Police Chief) will proceed onto Act 5; there are only two more acts left for them to clear now.