How we created an app to deliver emotions

A case-study of how we developed the Tricky Letters app using Lean UX and Lean Startup approach

Julia Nechaieva
Dec 2, 2013 · 10 min read

We are Tricky Eyes, a small design studio based in Moscow. We have recently created and launched Tricky Letters, an iPhone app that delivers daily inspiration to users in the form of visual letters. They arrive at unpredictable times via an engaging Mailbox character — the heart and soul of our app.

We came up with our initial idea, then submitted it to a series of experiments: first as a prototype for ourselves, then a version for a small group of people. Then we started production on the app for App Store. With each phase we set forth a hypothesis and found a way to test it. We want to show you how our app concept evolved and eventually took on its current form.

Our history

Julia, Sergey and Zoreslav

Back when we worked for a big game company we created iPad game for kids called Creativium. We liked the app development process so much that we decided to continue on our own. In April we founded our design studio Tricky Eyes; now we had total freedom.

Coming up with our idea and testing it on ourselves

We used different creative techniques and studied the App Store’s lists of top apps.

At one point we stumbled upon Bret Victor’s video in which he shows how to come up with ideas for games based on ordinary things that he sees throughout the day. We guided our brainstorming with this method.

During this process, we thought of the mailbox in our apartment building. Typical mailboxes in Russia are not in very good condition and are hardly a sight for sore eyes — you don’t look forward to checking your mail.

Looks horrible, hah?

But what if they were a joy to check, we thought? What if every time you saw your mailbox, you looked into it because you’re anticipating a letter? How happy would you be when you finally received it?

We jotted down the idea for an app where the player has such an inviting mailbox and receives letters in it. The player doesn’t know when a letter will come so she has to wait and check her mailbox regularly.

In order to test out this app idea, Sergey created a simple prototype in a few hours using CoffeeScript and Node.js. It was a web app that worked on only our local network. Julia would open the site by tapping its icon on her iPad home screen and check if she had received a letter. Sergey would manually upload the letters to the server.

Julia complained that the letters didn’t contain cute animals. So Sergey sent her a photo of Arnold. Next to some cute animals.

Our hypothesis was that Julia would check her Mailbox for at least 3 days.

Julia ended up checking her Mailbox for 5 days. She wanted to continue but Sergey had gotten tired of sending the letters.

Our hypothesis was confirmed in this simple experiment. Some insights that we got were:

— The sender does matter. Julia was waiting for letters from Sergey specifically and she wanted them to be personal.

— If Julia didn’t like a letter she became upset.

— The way Julia used the app was more likely the iPhone way of using than the iPad one: she opened the app more than 10 times a day.

Creating a prototype for real users

We kept the mechanics of random delivery time but decided to make the user’s experience more pure: we needed a real iPhone app.

We put together visual material for design inspiration: the Black Mirror series, David Lynch movies, vintage American ads from the ‘50s, and flat UI graphics from Dribble.

Sergey created some simple sketches. It’s interesting to note that the final app layout remains unchanged from these.

The idea of using flat graphics was born at this point.

To discover what kinds of letters people would like, we created several types of them. When the player received a letter the app would ask her if she liked it.

As mentioned above, the second prototype was made as a native iPhone app because we wanted people to have a real experience while using it. However, we tried to create it as quickly as possible. So we used graphics from Shutterstock, hardcoded all the algorithms, and created enough letters to last a week only. It took only 2 days for developer to develop this version.

We then selected a group of people to install this version of the app and play it. We chose 15 of our friends who are emotionally similar to Julia: they love modern design, value small joys, are open-minded and addicted to their iPhones. They all work with technology and web but would describe themselves more as product/design people than developer types.

Our hypothesis was that at least 50% of them would play for a week.

Everybody ended up playing for the whole week. We analyzed their behavior using app stats and interviews. We dug the most where what they told us was not confirmed by the data.

Through this process, we obtained a long list of discoveries. Here are four that we’ve selected:

We drank a lot of coffee during the interviews.

The way of using: our users checked the app every time they saw its icon on the iPhone screen.

Emotional connection: they were talking about Mailbox as about the living character and believed it was him who sent the letters.

Fortune cookie wisdom: our users liked the most the letters that they found relevant to their lives.

Disappointment: they didn’t like that there was nothing to do in the app when a letter hadn’t arrived yet.

Production phase

— To target an English-speaking audience.

— Everything had to be completed by the three of us within two months.

— It should run smoothly and be visually current. The App Store doesn’t forgive half-baked apps, nor do its users.

Mailbox character

We were inspired by Clifford Simak’s sci-fi stories about extraterrestrial creatures that influence people’s lives, the Hitchhiker’s Guide to the Galaxy, the FEZ game, Le Petit Prince, Wall-E and the Bender from “Futurama.”

Julia even wrote a story about Mailbox. It was bad, but it helped her further develop the Mailbox character.

Mailbox ended up becoming a self-sufficient, super-intelligent creature from another universe. He exists outside of our temporal plane. He knows more about people then they know about themselves. He is a kid and a grown-up at the same time. He wants to help, but he can also be very sarcastic. He is discovering our world and sometimes gets excited about it, but sometimes also tires of it.

Inspirational letters

We often buy many books. We order them on Amazon every month and also bring some back from every trip.

The short text of each letter would be accompanied by an image, to make for a complete message and fill the player with positive emotion.

Creating the letters was one of the favorite parts of the project for Julia.

We wanted the letters to look familiar, like your friend’s Instagram photo, or photos that you might take yourself. They should not be glossy, commercial-style photos like the ones in magazines.

Graphics and technology

Sergey chose a flat style because of its modernity and simplicity. He’d rather learn Cinema 4D then spend days polishing candy graphics.

We used 3D-editor to create the Mailbox. Sergey came up with a new aesthetic that he calls flat 3D. Mailbox was a 3D model that looked like flat graphics.

This approach allowed us to handle and change the graphics and animations easily. For example, we created dozens of versions of the app icon in a matter of minutes.

Mailbox talks to a player

Mailbox eventually acquired several thousand phrases to say to a player depending on the situation.

Some tips that helped us to develop rapidly

2. To create visual mock-ups for the app background themes, we borrowed graphics from other people to try out. It allowed us to experiment with different styles, compositions and settings without making a real drawing. The themes that we would settle on we later drew from scratch.

3. We used a lot of paper in our design work. For example, we printed out the app templates for sketching the background themes.

4. Our entire team had access to source code on GitHub, made commits to it, and could build the app without the developer’s help. Julia edited the dialog texts, and Sergey fixed typography and formatting. He also tweaked the shadow and animation settings. The app had a “god mode” that allowed us to jump immediately to the needed UX case to check it.

This efficient teamwork is one of the accomplishments that we are the proudest of with the Tricky Letters project.

We worked at our home studio.

OK, now the app was almost ready; time to present it to the public.

Release day and afterwards

Answer: They were launched on the same date: September, 17th. It was not our finest hour at press.Never again will we plan our releases at the same time with rockstar companies. At least not until we become just as big.

We were not going to push marketing from the very beginning. What we needed was to obtain a specific number of app downloads in order to test our hypothesis.We wanted to measure how people like our app through one metric: retention.

We drew a line on the sand that at least 80% of users will stay by the second day and at least 40% will stay by the 7th day.

We made the app paid from the very beginning to have only users who saw value in the app. wrote a review of Tricky Letters that helped push it into the top 50 of paid Lifestyle apps in the US. Then some organic traffic came. We reached our download goal very quickly.

Retention was greater than we had expected: 85% of users stayed through the second day and 65% stayed through the 7th. It was clear that users liked our app; they expressed this in reviews and the data confirmed it.

The second thing that we are the proudest of with Tricky Letters is the Mailbox character. People got him just the way we intended. They wrote us “what a jerk is this Mailbox :)”, “what a cute thing”, “my friend Mailbox”.

We even heard of one interesting way that people use Tricky Letters: one girl told us that she took screenshots of Mailbox when he talked to her and sent them to her friends.


However, our story with Tricky Letters is finished at this point. The people who sponsored our development will continue with the app on their own. We wish you good luck, guys!


P.S. If you found value in this article or have something to share with us, you can always write us a would be happy to hear from you!

    Julia Nechaieva

    Written by

    Product Manager at Google. UC Berkeley Haas MBA. Post-internet artist. San Francisco.