This option selects the language for any text on the finished puzzle that the user doesn't directly control.
You will probably notice that there aren't enough languages here. Feel free to drop me a note (see "Report Bug" to the left) that tells me:
I realize that Arabic (and some other languages) are written from right to left. This isn't handled well yet. I'm sorry about that.
Some things that need to change for right to left languages are:
Note that the Welsh language is a little different from other languages in the way it represents a character with two keyboard symbols. See http://en.wikipedia.org/wiki/Welsh_orthography for more information on how this works.