ah yes, F_ckScript, my favorite coding language.

what purpose does the i-forloop serve?

just wondering, why convert to a chararray explicitely?
a string is per definition an array of chars.

it wouldn't, since -7+(-10)>5 would return false ;)

clever way to check if there's a 0 amongst the abc :)

oh, okay, didn't take the actual definition in consideration when solving the Kata.

Does it test for a case where one of the words is only 1 symbol long?
Because I have a solution, but I think it wouldn't work in that case.

read the task again...
You have to switch the letters in each word, not each word in the sentance.

challenge mentions that it expects "" on an empty set.

The fluff mentions this.
the name only is there for historical reasons.

no, you'd have "" as a result.
you need to give back the first char that is unique as a String.
abba contains no unique chars (2a's and 2b's). if it was abb, it should return a.

int _ = 0;
could just be int _;
it's a small thing, but you don't have to assign a value to a newly declared variable.