The reason for me deducting a half star was because of a tiny bug. The letters only fit in the squares if you place them right under or to the right of the square. This is particularly troublesome when you have to drag to the left. It may cost only a couple of seconds, but it was enough for me not to achieve 1st place overall.
One nitpick: it could be useful for us who are not native English-speakers to include some definition, particularly for the longer words.
Otherwise, nicely done game.