After you win a few rounds, it lets you suggest a new puzzle (subject to approval). I just checked and was surprised to find that there were over 50 new suggested puzzles. I clearly need to build some additional functionality into my approval page, as many of the suggestions are spelled incorrectly or are missing punctuation.
well_lahdidah suggested that the application should offer words or phrases of appropriate difficulty to players, kind of like the computerized SATs or the new Free Rice vocabulary quiz. I haven't implemented anything like that, but the application does track how many times each phrase is played and how many times it is completed successfully – down the road I could use the data to tailor puzzles to players.
It's been reasonably well tested, but there could very well be a few bugs – let me know if you run into any unexpected behavior.