@ISU -- You accidently copied the "ISWorld" style into the set folder. The very first level is with the ISWorld style -- and so are about 10 or so levels in the entire pack series.
"Twin Paradox 2" is a back-route, and one I can't seem to think of how to fix right now. Granted, Ahribar, your solution isn't THAT much different than mine, although mine is set up so that you need the climber.
"The Careless Level" is not meant to be directly cleared. A simple piece of steel may be able to fix that back-route. Looks like the title was more accurate than I intended. X_X
"The Narrows" has a certain trick-ish thing required to pass it; it isn't a "direct, fudge the level" kind of level. Can you send me your solution so I can see if I can remove it (If it's too different than I had intended)?
Thanks for the comments thus far -- The first few levels of each set should be somewhat easier than the last levels of the previous set -- when I first made these levels, it was assumed that the player would not be able to play the levels in any order, so I set it up so the first few levels of a set were a bit easy overall.