Well, assuming when the game begins you save the correct answer to %hm.answer and the "guessed" answer to %hm.guessed ad the letters already picked in %hm.picked you can use soemthing like...

Code:
on 1:TEXT:*:#: {
  ; its just one letter
  if ($len($1-) == 1) {
    if ($1 isin $picked) { /msg $chan The letter $1 was already said. }
    else {
      /set %hm.picked $addtok(%hm.picked, $1, 44)
      /hm.guess $chan $1
    }
  }
}

; Here are our fake vars for now to give some idea as to how it would work
; %hm.answer online
; %hm.guessed ---i-e
; %hm.picket aei

; Syntax: /hm.guess Channel Letter
alias hm.guess {
  ; unset the temporary guessed var
  /unset %temp

  ; cycle through each letter individually
  /set %a 1
  while (%a <= $len(%hm.answer)) {
    if ($mid(%hm.guessed, %a, 1) == -) {
      if ($mid(%hm.answer, %a, 1) == $2) { /set %temp $+(%temp,$2) }
      else { /set %temp $+(%temp,-) }
    }
    else if ($mid(%hm.guessed, %a, 1) == $chr(32)) { /set %temp $+(%temp,.) }
    else { /set %temp $+(%temp,$mid(%hm.guessed, %a, 1)) }

    ; increase loop var (-u0 means kill the variable after executing it)
    /inc -u0 %a
  }

  ; Now, replace the guessed with the temp variable (also convert all the .'s to spaces)
  /set %hm.guessed $replace(%temp, ., $chr(32))
  /unset %temp

  ; announce result to the users
  /msg $1 Current Word: %hm.guessed
}


now, all this does is goies through every letter looking for a match. When it find one, it replaces the - with the letter in the "guessed" variable. You might want to check the variable after each time hm.guess is executed to see if any more -'s exist. If nomore are in the frase, then you can assume the user has guessed the word. >:D

*Edited: Few errors >:\

-KingTomato