Hangman is of very dubious pedagogical value IMHO, it uses an inordinate amount of time to focus on single words.
Far better is
Board Boggle in which you draw a 5x5 grid on the board with letters ellicited from students (be sure to be tactical and abitrarily stick a few vowels in there) or you can make your own up if time is short.
In 2's-3's Students have 10-15 minutes to find as many words as they can...
Words can be found in the grid by following chains in any direction vertically. horizontally or diagonally, using each letter only once per word
They score points for each word as follows:
minimum 3 letters =1
4 letters = 2
5 letters= 3
6 letters = 4
7+ = ? (bonus ie make it up as you go along)
After students swap papers shout out some answers and you write them down saying yes or no (half of them will have the same words anyway)....get them to add the scores up.
You might also make a mental note of the longer words and teach them as random vocab. (A decent English - Farrang - Thai dictionary might be an idea here)
For those unfamiliar with the classic word game a very addictive online version can be found here.
http://weboggle.shackworks.com/