Nice game, Mark! Really impressive.
I love the tap-tap suggestion for placing letters. One extra idea on top of that one – instead of tapping the letter in the tray first, and then the location, have the player tap the location first and then the letter. Combine that with the following: once the player has placed two letters, start auto-highlighting the next location. (In fact, even after the first letter is placed, take a guess as to the location of the next letter, of either one to the right, or one below.) Then, if the auto-highlight is the next location they wanted, the player can just tap the letter tile. In other words, to place a five-letter word, they’d tap the location for the first letter, then the first letter itself, and then if the auto-highlight guesses the right direction, they could just tap the second through fifth letters without having to tap the board again. If it happened that the auto-highlight wasn’t where they wanted it, then they’d first tap the board (to move the highlight) and then tap the letter.
You could make the auto-highlight really smart, and skip over existing letters to highlight the next open spot in that direction.
One other request: at the start of the game, maybe a sound effect that lets you know the timer has begun. And it would be helpful if the “next level” tiles glowed for a moment, just to help you see where they are. (Even better, for me, would be to have a few free seconds to study the board – perhaps the board appears, the “next level” tiles glow, and you get a couple of seconds to look around, and then the letters appear on the tray and the timer starts.)
Okay, gonna go play some more… 