But there's one important exception: If you box in a blue tile with other blue tiles--that is, if you completely surround a blue tile with other blue tiles--it turns a darker shade of blue. Even if your opponent spells a word using such a tile, its color won't flip to pink. A key strategic element in Letterpress is thus attempting to box in your own tiles to lock their color, and simultaneously scheming to unblock your opponent's tiles.

Once all the tiles have been used (or after both players skip a turn), the game ends. Whichever player turned more tiles to his or her color emerges the victor.

I tested the game for several weeks, and I frequently had numerous games going. Letterpress is fun and compelling enough that I needed to remind myself to put my iPhone down and, say, eat.

Nice touches abound: the cute sounds that accompany each gameplay move, the bubbles that indicate what word your opponent just played, and--my personal favorite--the brilliant thumbnails that accompany each game in your game list: Each is a stripped-down white, pink, and blue square that indicates the current state of the board for that game.

There's room for improvement. I'd love the option to chat with my opponent; shunting trash-talk to a Messages back channel seems like an unnecessary extra step. And--though I recognize space becomes a serious constraint here--I'd love for Letterpress to provide some indication that I'm attempting to form an already-played word; in games that stretch on for several days, it's easy to forget you're building a word that's already been played, and annoying to tap to the screen that lists all those past turns.