Go right, paying attention to the enemies on the cannons, who will shoot you. Duck or jump to avoid the cannonballs. When you get the chance, pull yourself up and you will have the choice between Arrow Gas on the right and Thunder Gas on the left. Keep going and when you still have a chance to go up to the upper level, do so, to find a Heavy Gas (if you want it) and a Darkwing Doll at the bottom left. Go back downstairs and continue to the right, carefully defeating the enemies on the steps. Then drop into the gap at the bottom, holding on to the rope and moving left to avoid the spikes. Go down again, using another rope and continue to the right.
You will have to face an enemy that you can only hit from the back and other enemies already seen in the woods. To continue, you will have to hang on to levers, in order to make platforms appear. Move quickly though, because after a few moments they disappear. Then go down into another gap, carefully avoiding the spikes. Go left grabbing the rope to avoid the spikes, drop down and continue to the right.
Here you will encounter some very tough enemies. At first they will shoot you with a machine gun; avoid their attacks and shoot them back. When you have landed a certain number of hits, the enemies will transform and charge you without ever stopping. At this point you will have to hit them quickly, perhaps with a special weapon, or just jump over them. Eventually, they will transform again and start jumping: at this point a single shot will be enough to eliminate them permanently. Other enemies will hide inside barrels - be prepared to avoid this barrel when they throw it at you. You will then have to overcome a long area with no floor, holding on to the hooks. Be careful not to fall. You will come to a point where you can grab two large gas energy canisters on the left and a large first aid kit on the right. Soon after, you'll find a Heavy Gas and a Thunder Gas on a platform. Continue jumping from platform to platform, paying attention to the enemies with the machine gun. Finally, on a ledge you will find a Darkwing Doll and another large gas energy canister. Go down and defeat one last enemy with the machine gun. This time you won't be able to jump over it, you will be forced to kill it. Finally enter right to finally meet Steelbeak.
BOSS FIGHT - STEELBEAK
In the first phase of the fight, Steelbeak will remain in a control room in the upper right corner. He won't attack you personally, but there will be two flying robots chasing you, flying around the room and firing purple bullets at you. You can defeat them with your weapons, but if you destroy them, more will appear a moment later. To pass this stage, you will have to destroy the glass that protects Steelbeak. If you have Thunder Gas you can try to hit it while remaining on the ground, using this weapon. If you don't have it, the best thing to do is get to the top left candlestick as soon as possible while destroying the two flying robots. From this position, facing right, you can easily jump and shoot, hitting the glass. In addition, you can immediately hit the new robots that will continually descend from above, to replace the destroyed ones. When you have destroyed the glass, Steelbeak will drop to the ground and a large first aid kit will appear in the control room. Grab it, go through the broken glass and drop to the ground.
The second part of the battle is much easier. There will be no more flying robots to sneak up on you. Steelbeak will just run quickly back and forth around the room. You can easily avoid it by jumping and hitting it with your weapons whenever you have the opportunity. Every now and then Steelbeak will stop, protecting himself with a metal shield, which he will then throw at you. Quickly jump to avoid it and resume attacking Steelbeak. As always, if you have Arrow Gas, you will inflict massive damage. Keep hitting Steelbeak to finally defeat him and complete the game.