When you arrive in this stage, you immediately jump down a pit and fall for a bit before your parachute deploys. You arrive in a sewer area. Walking along the pipes are a group of gremlins. The gremlins you encounter early on do nothing but jump around on the pipes. Defeat them and use the pipes to navigate over to the right. Note that there is a grate between two platforms above the rushing water which you can not stand on. If you try to walk across it, you will fall in the water and lose a life.
Once you get far enough to the right, you must begin climbing. The challenge here, however, is that the gremlins above you will start munching on the pipes and cause parts of them to fall down. If you are standing directly beneath them as they fall, you will get hit and lose a life. After some time, the broken pipes regenerate just as the broken branches did in Stage 1. The hardest part is timing your approach to the pipes above you and taking out the gremlins so that you can proceed up to the section above the sewer. If possible, stick to the left side, and try to grapple up to the small edges behind where the gremlins sit.
Once you rise above the last gremlin, you won't see them any more. You will, however, see a lot of soldiers running around the room that you just arrived in. In addition to soldiers, there will be two mech pilots steering two large robots in an effort to stop you. They are piloted by short soldiers, which you will also see flipping around. When these short soldiers shoot, they fire low to the ground so you can't duck under the bullets. If you run to the right side of the floor, you will likely see a red gun floating down. The red gun is very effective against the mechs, so grab it if you can.
As you climb up to the top of the room, you will see a platform that travels back and forth suspended from the ceiling. If you climb up via the right side of the room, it's not necessary to utilize the platform, but if you traveled up the left side, the platform makes a convenient shortcut to the pathway above the room. Note that you can grapple to the ceiling above the platform, but you can't actually grapple to the platform itself.
Above the room with the platform, you must make your way a short distance to the left. More soldiers will attack you, including another mech pilot. Pay close attention to the soldiers, a few may toss red grenades at you as you approach. Do your best to pick off all of the threats before you start rising up the green scaffolding to section above. As you get to the top, you'll have to be especially careful of another mech pilot that limits your freedom of movement.
When you reach the top, you should see a panel that resembles elevator buttons (up and down). You must shoot these panels in order to make the large doors rise and gain access to the area beyond. Around the time that you shoot the first one, a blue gun should be floating down. When you proceed into the next section, you will be greeted by an extremely large red armored robot. The robot stays in one position, although its legs and arms will move around. Contact with the feet or hands is deadly. You must time your passage past the robot so that you successfully run beneath the feet and up to the platforms above, where you can swing over the hand.
Continuing on past the first robot, you will encounter two more. The legs of the second one are hidden behind the ground, but its hands will be moving. Once you pass the second robot, you'll have another full sized robot to deal with. All around you, more soldiers will appear, so it's a good idea to clear as many of them out before you attempt to pass the robots.
While attempting to sneak past the third and final robot, you will see two door panels. The bottom one is much easier to shoot, as the second one can only be hit while you are rising up with the grappling hook. However, be aware that the bottom door leaves a gap in the floor that is easy to fall into. It's better to grapple diagonally to the platform above and swing into the next room. In this final room, there will be a few soldiers, including another mech pilot. But more importantly, there are two captains. In order to clear this stage, you must successfully defeat both captains. They won't put up a tremendous fight, just make sure there are no other threats in the room while you take them out. In order to defeat them safely, duck down while you shoot at them.
