In truth - no, Candy hasn't created a whole new language. By no means. What Vánan actually is, is a "butchered" version of Finnish. There are some rules for changing the spellings, and other than that I try for an aesthetically pleasing result. My goal, meaning-wise, is that Vánan can't immediately be recognized for a crude, clumsy version of Finnish, but at least after reading a translation, any Finnish-speaker should be able to see the connection.
I hope you will forgive my lack of accurate linguistic terminology. I'm not a linguistic - yet, at least. The info I've gleaned from the entrance exam books is still sinking in. :)
Spelling rules
Some letters are systematically changed for another when going from Finnish to Vánan. On the left the Finnish letter, on the right the Vánan.
j = y (note that still y = y)
k = c
f = ph
Long vowels are written with an accent. Thus:
aa = á
Doubling of "hard consonants" is not allowed, as per the aesthetism guideline. Thus:
cc, pp, rr, dd, tt - not allowed, possibly some others
I'm not yet sure if to only shorten these to single consonants or something else. Will have to decide.