This and the next level will be along the toughest in the Europe/grassland section. Get ready to fight your way through this level.
Stinky Sewers
You'll be going through the sewers for this one. You'll be playing as a rat for the majority of this level. You'll need to find a keycard to access the main tunnels, reactivate the Big Taps (which are big water taps) and gain access to the King Rat's hole. From here, you're going to have to defeat the Rat King.
You'll start off not as the rat, but as the racing dog. You'll need to find your way through the sewers and find and defeat a rat while trying to find out how to complete the objectives for this level.
The steaming brown triangles are poop. Believe it or not, these things will come into play later.
Once you find a rat, you'll be able to go into some of the more narrow passageways. You'll have to fight some more rats to get them out of your way. Use your bite attack and move in as they move around in circle, and watch out for their mines. You'll eventually find a much more open area with a racing fox. You'll need to race around the room and drop mines as the fox chases after you in order to destroy it. If you need health, eat the steaming poop in the room. Just walk into it with the rat and use your bite attack to eat it. Believe it or not, if you find all the poop and eat it, you'll reveal the trophy, which will be in a dead end the near the start.
From here, you'll need to take control of the fox and make your way back to the watery maze at the beginning of the level. Believe ir or not, there are areas that you can reach as the fox or the rat that you could not reach with the racing dog. There is a crawlspace near two barrels of toxic waste that you need to go through. Take out the rats, then approach the door to open it and find a dead scientist. Move up to him to find the keycard. This will allow you to open the metal door near the beginning of the stage.
Once you're past that door, you'll have to fight some more rats. Fighting the rats is easier with the fox, since the sweep attack does not trigger the bombs and you can do a good bit of damage with it. On the other hand, it's much easier to get close to another rat and defeat it easily with a bite attack as the rat. Keep your options open and pick your poison. After getting past the rat, use the mines from the rat to blow up the line of barrels of toxic waste, and stay away from the explosions!
There is an area full of water after this, but you don't want to go in there yet. Instead, look for and find a water valve. Run into it to turn on one of the Big Taps and add more water to the nearby pool of water. Go in the water, and you'll find a normal dog. Switch to the dog, and push the barrel in the water to create a path to the other side of the pool, where you can find a racing dog.
Take control of the fox again and go back to the side of the pool that you were just in. There is a narrow corridor leading into another maze that you'll need to get through to reach the Rat King. The colors will change as you go through the maze, and if you see a lot of yellow and green, you'll know that you're nearly there.
To beat the Rat King, you'll want to play as the fox and you'll want to come in with as much energy as you can muster. The Rat King will send smaller rats at you when it blows its trumpet. You'll want to stay near the entrance to the Rat King's chamber, attack the rats when they get near, and move out in such a way that you lose as little energy as possible. There are two crates' worth of energy that you may have to rush into the room to get; if you have to rely on it, make sure that the energy does not fly towards the wall, as it can get stuck in the wall and become unobtainable.
Once you beat all of the rats, take control of one and chase after the Rat King. The Rat King will have no means of offense other than a stink cloud that only affects other animals, and he won't be able to send any other minions at you. Once you've beaten this level, you're pretty much done. All you have to do is find the door near the start that had the symbol of a crown near it and approach it as the Rat King to open it. You can then exit the level.
King Rat
Type: King Rat
Environment: Europe
Skill A: Ratty Smell
Skill B: Rat Army Attack
Water Resistance: OK
Mass: Medium
Armour: Light
Strength: Medium
Traction: Average
Fall Distance: Medium
Production: Medium
Engine: Diesel
Intelligence: Very High