m a s t e r m i n d ( f o u r - l e t t e r )
This game is similar to regular mastermind played with letters. The
program chooses a valid four letter word, and the player is supposed to guess
that word in 15 attempts. Each attempt must be a valid word. The program takes
some time to load the word lists, so you'll need some patience. Check out the
detailed rules here.
If you find this too easy, try the five-letter version