This world is dedicated to Dark Kat and is the only one that can be played only once in a run (the player still gets a password after completing it in order to continue the game at the point before entering world 5 while having the current experience level).
It’s kind of a mashup of all of the Dark Kat episodes of the first season and begins with Callie Briggs being kidnapped by Hard Drive. Having transformed into a lightning bolt he lures the SWAT Kats to an old mill. On his way there and inside the mill the selected SWAT Kat encounters mostly Dark Kat’s Creeplings, but there are also some other enemies, like sabertoothed tigers which look a bit like the one appearing in The Pastmaster Always Rings Twice. After surviving the obstacles inside and below the mill, Hard Drive takes Callie to the Doomsday Express which starts immediately. The SWAT Kats follow it in the Turbokat, crushing their plane into the Doomsday Express in kind of a kamikaze act. Once inside the ship the player has to face and defeat Hard Drive in a mini-boss battle. When leaving the ship the SWAT Kat finds himself inside Dark Kat’s lava fortress and faces Dark Kat himself who has tied up Callie. But before reaching Dark Kat the ground breaks away taking the SWAT Kat down with it. After facing more obstacles the player finally has to face Dark Kat in a boss battle. But before he can actually attack Dark Kat himself he first shot of the arms and a head of a skeleton gargoyle. When Dark Kat is defeated the SWAT Kat unties Callie and the game ends with a cutscene which is funny and in some way disappointing at the same time.
This is the shortest Turbokat section and the only thing you have to do is to evade the shots from Dark Kat’s Doomsday Express until the Turbokat crashes into it in a kamikaze alike style.
When encountering Hard Drive you should try to avoid his electric shots and also himself being an electric bolt.
Once he manifests in his true form don’t stand too close to him when you’re firing your shots at him.
This is the hardest of all boss battles (Yeah, it’s Dark Kat alright!).
First you have to deal with his big gargoyle alike creature. Concentrate your fire on the hands as they fire shots at the SWAT Kat that gonna follow him. When your level is high enough (about 75) the range of your Glovatrix is sufficient to hit both hands of the gargoyle with each shot when you are close enough. Be careful as the ground will break away after a few seconds. In order to survive this you need to be close to the left or right end of the stage. Once the hands are down, attack the head of the creature and avoid the fireballs it spits. Once this is done you have to fight Dark Kat himself. Try to hit him as often as possible while he’s floating around. When he draws his gun try to position yourself at a spot where there is enough space between the shots to jump through. As soon as he starts firing small round shots from his platform, get to one of the corners of the stage as Dark Kat is gonna drill one of the blocks building the floor away. In order not to fall into the gap later it’s best to have it in a corner. The best weapon against Dark Kat is having a very high level, hence dealing more damage (Dark Kat can take quite a lot of it!) and being able to take more hits yourself.