Ciphertext with uneven letter distribution I have a ciphertext encrypted with an unknown method. It is part of a challenge (personal quest), so I can not post it.
The letter statistics is the following:

y : 10
w : 8
x : 8
t : 5
v : 5
e : 5
c : 5
d : 5
u : 4
z : 4
f : 3
b : 2


Because of the uneven letter distribution and repeating two letter sentences, I tried to approach as a monoalphabetic substitution cipher without luck. I tried manually and also with this python code.

The previous challenge was a Caesar cipher, so I do not expect any complicated method. Are there other encryption methods which produce such a letter distribution?

UPDATE: I am no more interested in this challenge. Here is the whole question, if someone is interested:

This is your first personal quest. Decipher it in order to access Level Two!
But before that, a little something to put you on rails. Easy as 1-2-3:
hotstteitmegpdnoctnooruglsmloabsnheismralgyeasjlsacshhlwssznlusmablesrafhosuprh

Don't fear the random(). Some even seek for it...
VXZDVWWWFYBWYWWCEUWWFXZXZUEYDTETXTXYZDVXVYDYBCYECTXYYDCEFUTUCXVY
I would have expected Vigenère and Playfair ciphers to reduce the skew in the letter distribution, so I think you can rule them out for the time being. Here are some other things you could consider:


Perhaps one of the letters corresponds to a space:


  hello world &rarr; itssgxvgksr

Perhaps there is no letter "e" in the plaintext


  A Void by G. Adair &rarr; Q Cgor wn U. Qrqok

Perhaps the text was encrypted using a monoalphabetic cipher with homophones (so that two or more letters in the ciphertext correspond to the same letter in the plaintext)


  hello world &rarr; itxyg vgkxr

Perhaps the text was encrypted with an additional transposition step


  hello world &rarr; itssgvgksr &rarr; isggstsvkr

If the ciphertext contains mixed upper and lower case letters, then perhaps it's just been Base64 encoded:


  hello, world &rarr; aGVsbG8sIHdvcmxk

If the letters are printed using different styles (e.g., different colours or sizes), then perhaps this is a Baconian cipher


  hello &rarr; 00111 00100 01011 01011 01110 &rarr; rrvuv ysljq akjsz amshc wvieh