Because Letterpress is lacking gradients, drop shadows, and other embellishments, the Google Product Manager in me decided to take it apart and analyze what makes it a great experience. I found no bells and whistles, just carefully executed transitions and animations at every step.
I present to you Letterpress, deconstructed.
If you haven't heard about Letterpress, it's a word game where you have to form words with letters on a 5x5 grid. When you use a letter, that turns it blue. When your friend uses a letter to form a word, those letters turn red. Once the entire grid is covered in red and blue, the letters are counted up and if there's more blue than red, you win. It looks like this:
The Story Behind Letterpress
Why It Works
Wait spinner: Since Letterpress has to load the current game state from the web, a user will see the wait spinner pretty often. The Letterpress wait spinner is the company's logo. This has long-term brand benefits. But also it's cute and well-executed. Every 8 turns, it randomly spins backwards to give it some personality. This is apparently in reference to the company's name (atebits = 8 bits).
Clear animation: Clearing the word in a game makes the tiles animate back to their original location.
Game Center: I'm undecided on whether this is a benefit. Game Center allows Letterpress to piggyback on the existing social graph of iOS. Thus it doesn't have to deal with the messiness of integrating with Facebook directly to match you up with friends. But two things speak against it: First, Game Center is ugly and soils the look of Letterpress. Second, Game Center's screens are a bit too complicated for the average user to understand and thus cause a bit of churn: For example, what does "Invite up to 1 player" mean in the friend selection screen? You should just click on one and the game should start. In addition, Game Center's design is uncharacteristically kitschy for a core iOS app and going between this and Letterpress feels jarring.
Not Rocket ScienceOverall, none of this is rocket science. I'm pretty sure that all of this could have been done with UIKit, but it turns out Brichter implemented his own animation engine in OpenGL . What sets Letterpress apart is that there are few screens and little complexity, every screen in the app is thoroughly executed, and every transition is carefully animated. Nothing you or I couldn't do. "Modern art is when you could have done it, but you didn't," the saying goes, and it is also true for Letterpress.
Conversation on Hacker News
Notes and Corrections
 The original version of the article stated "This is all UIKit", but the animation engine is actually implemented in OpenGL (thanks to wallflower on Hacker News for the tip)
 The original version of the article said that "the app and its website play the mystery card", but the website actually provides some background about the origins. I changed the post to reflect this. (thanks to pflats on Hacker News for the tip)
 The original version of this article said that "Sometimes the spinner randomly spins backwards", but xuki points out on Hacker News that it's actually once every 8 turns.
 Great point by nbashaw on Hacker News on the game mechanics of Letterpress: "I love how letterpress is really a territory game disguised as a word game. Instead of rolling a dice like you do in Risk, you find words to form your attacks. Rather than trying to pick up words with obscure letters, or lengthy words, you try to capture strategic tiles and expand your controlled area. Once you cover a large area of dark blue tiles, you choke out your opponent's ability to score points, and the game slowly snowballs further in your favor. It's really fascinating."