Yay!!! Complicated Problems which distract me from homework!!!!
in a fair game of hangman, only the 26 letters are generally used, you sometimes can get away with something like n00b, or l33t, or ?, but after you do it once they will probably tell you to stop. using every character in the English language is for people who can't think of any good ones normally, also since there are pronouns for everything, and new ones are made constantly, they are cheap. you only have truly whooped your opponent if it is a word they actually could have known.
with this junk in mind, the important things to consider in a hangman word are as follows;
1) Word Length
a) a good word is short. if there are more than 10 letters, the probability of any given letter being in it increases. Also, the number of words it could be falls considerably, and there will probably be enough repeated letters that someone can find the complete word after only a couple guesses.
b)a good word is not too short. there are three one letter words, so someone is guaranteed to never make more than two wrong guesses. 3 is similar, and you only start to see a really wide range of possibility's once you get to around 4 letters.
- IMAO the best #of letters is inbetween 5 and 8. on either side of that range you start seeing vocabulary limitation, which can help your opponent.
2) Letter Distribution
oh, the mother of all hangman words. to use an optimal letter distribution, you need to know that there are basically four kinds of players, each with their own weaknesses. a n00b who likes vowels (or even picks randomly, heaven forbid!), a Enlightened n00b who likes e,t,a,o,i,n, and s, a skeptical n00b who will quickly switch over to memorable uncommon letters x, j, q, and z after they miss a few, and the pro, who can reverse engineer your strategy and counter it based on the same tedious psychological manipulation which you are using.
after someone guesses their first couple letters they may start to see patterns in the words that it could still form. some words are easy to finish after guessing less than half of the letters, since there are only a few combination's of letters that could possibly finish the word, but others leave dozens of options for how you could finish them. for this reason, words like "Quiz" and "Lynx" lose some of their value as words (though they are still awesome for inverse distro), while words like "Hack" or "Soft" actually are more challenging then they look.
if nobody is familiar with the word they are trying to guess, then they can't use similarity's to guess the next letter, in fact, banking on something looking like other words and trying to guess letters according to this plays right into a 3 from the hangman. obscure words are pretty much always better than common words, but this is hard to do if you are playing against someone who is more fluent than you, so a bit of research somewhere like http://www.islandnet.com/~egbird/dict/dict.htm
can be useful.
with all this said, my favorite hangman words are winx, jerque, qasida, dyvors and fruzz.