I haven't been truly excited about a new iPhone in a very long time.

Over the years, new iPhone models have often just been thinner and faster, with cameras that also saw impressive upgrades. At a certain point—apple fans can even argue about which year the trend began—new iPhone models represented a kind of gradual improvement: slightly better, slightly faster. There might be a new button to learn to use, a new charging cable, or a new notch on the screen, but the iPhone itself remained that same consistent rectangular glass-and-metal handheld device.

iPhone Duo changed this. It allowed Apple to enter the foldable screen phone market, launching a phone that may not be perfect, but is full of creative ideas, fun to use, and, to be honest, truly exciting.

It's hard to say exactly when I first started thinking about buying iPhone and Duo. I have to admit that this urge didn't arise at any official press conferences; at that time, I was still confused about the potential of this device. Did I really want a foldable phone? I wondered to myself, is it really worth spending so much money to be able to prop up the phone like a small tent to view Netflix? (The starting price of Duo is $2000.)

It turns out that as I saw developers start to embrace this new folding design and create applications optimized specifically for Duo, my interest in this phone gradually grew. After all, it is Apple's developer community that has kept me within the iPhone ecosystem. Apple developers are active, creative, highly engaged, and they tend to prioritize developing for iOS – which is crucial if you enjoy trying new things.

Of course, the initial Duo evaluations also pointed out that many mainstream iOS applications were not yet prepared for Duo. This is indeed true. Many of the applications you use daily had not completed optimization on the day of release, which led to issues such as black borders, strange positions of control buttons, or the need to click once to zoom in, similar to the experience of running iPhone applications on iPad in earlier years.

But those applications specifically developed for Duo caught my attention. Soon, my inbox was filled with introductions to various clever apps, and without getting a Duo, I wouldn’t be able to try them out myself. Welcome to “Fear of Missing Out” ( FOMO ).

Among these applications, the most outstanding one not only adapts its interface to foldable screens but also makes full use of the different sizes of dual-screen devices, integrating this feature into the design of the application itself.

Below are some of my favorite applications from earlier times, all tested on the evaluation machines provided by Apple.

Netflix

Let's start with the basics. Netflix is one of the partners selected by Apple for Duo. By the time the device was released, its streaming media app had already undergone Duo optimization. There were also other apps such as MLB, NYT Cooking, Slack, and my favorite calendar app, Fantastical, among others. However, Netflix best demonstrates what I consider to be the most common usage scenarios for Duo: watching movies and TV series.

This streaming media app doesn't just simply stretch the content to fill the screen; instead, it takes advantage of the different screen sizes of the dual-screen setup to design a unique user experience. On the outer screen – which is what you see when the device is folded – you can browse short videos similar to “Clips” (similar to “TikTok”). Then, when you unfold the device, you can continue watching the video on the larger, matte inner screen. The transition between these two viewing experiences is just as smooth as unfolding the device itself, as the content automatically adapts to the new screen size.

These days, I mostly watch TV on my phone rather than on the big screen in the living room. Therefore, I really appreciate the option to switch between my phone and a larger screen with just one device. I think this will become one of my most frequently used applications.

Deck-Man (formerly known as Duo-Man)

Look, I said it back in September. I really have to give credit to Deck-Man – it was previously known as Duo-Man – because it was the first app that made me want to buy Duo. This music player was designed by independent developer Vidit Bhargava during a hackathon, and it cleverly utilizes the dual-screen feature of Duo to mimic the operation of old-fashioned Walkman cassette tape players.

This fun-filled app reimagines the tape player as a digital experience with a vintage vibe: you can browse your favorite albums as if flipping through tapes, and then “load” them into the player. Next, you can control playback just like you would with a hardware device, using functions like play, pause, fast forward, and rewind. There are even click sounds and the noises of the tape itself, and these sounds are recorded from a real portable tape player.

When Duo is expanded, a tape will appear on the right side of the screen, accompanied by an album image. When it is closed, the interface of Deck-Man looks just like the front of a Walkman.

The appeal of this app lies not only in its creation of something that could only exist on a foldable device with hinges, like the Duo, but also in its catering to the growing demand for retro technology, which to some extent is a cultural response to the AI industry's rapid release of new products. Retro technologies such as feature phones, digital cameras, vinyl records, CD, and landline telephones remind us of an era when technology was used more consciously, rather than being embedded in every aspect of life.

To be honest, if you buy Duo but don't install Deck-Man, I'll think you have no idea what fun is.

TypeDraw

The original intention of designing TypeDraw was to create a personal notebook that looked like a virtual Moleskine, and it even came with a elastic band closure. However, when used on a Duo, it possesses a special charm, as the form of Duo when closed closely resembles that of a small notebook.

In TypeDraw, you can input using your own handwriting style, or you can choose from one of the more than a dozen fonts designed by the developer Phil Traut.

You can also choose what kind of paper to use, such as lined paper, grid paper, or dot matrix paper, and pick the color of the ink. You can also draw and doodle to create colorful images that complement the handwritten text, making it feel more like keeping a diary in a real notebook, rather than using some boring to-do list app.

When scrolling through the pages, the page will curl up, and you can even pull on the elastic band to trigger a popping animation; it’s just for fun.

Wakeout

The fitness app Wakeout, which has won Apple's Annual App Award, has also made dedicated optimizations for Duo, designing different user interfaces for various phone positions. This app offers a series of mini exercise intervals that feel more like games than actual workouts, and it can be used when the Duo is closed, unfolded, in tent mode, or even when it's opened like a laptop.

For example, when Duo unfolds like a book, the interface splits into two halves along a hinge, with the motion gaming video displayed on the left side; but when it opens like a laptop, the video switches to vertical screen display. You can also set it in tent mode, which makes it very convenient to watch videos with Duo propped up on the table. (Most people use Wakeout while working, and then take a few minutes to stretch after sitting for long periods at their desks.)

Flighty

Flighty has become one of my favorite travel apps. This app, which has won an Apple Design Award, tells you everything you need to know about the flight you are about to take, from changes in boarding gates and delays to the status of the airport, and even the aircraft model.

But on iPhone Duo, when expanded, the application will utilize a larger screen space to display the map to the edges, allowing you to see more flight routes on a globe that can be rotated under your fingertips.

When Duo is expanded, the flight details will move to the left side of the screen, but it will not fill that entire side of the screen. Instead, most of the display area is occupied by a globe image, allowing you to zoom in on different routes more carefully when planning your journey.

This app also supports split-screen mode, which means you can track your flights while doing other things – like watching your favorite TV series.

In addition, Flighty has specifically added a new feature called En Route Mode for Duo. In this mode, Duo will fold into a tent shape and be placed on a flat surface—such as an airplane tray table. This way, you can use Wi-Fi to check the flight progress while doing other things, such as listening to music, reading a book, or watching movies on the screen on the back of the seat in the in-flight entertainment system.

Tiny Computers

Tiny Computers is an application designed specifically for Duo, and it is also aimed at technology enthusiasts – who are also among the first group of users of Duo. It provides an interesting way to reconnect with older technologies. The app comes pre-installed with 10 vintage computers for users to explore, including Macintosh, Commodore 64, IBM PC, Amiga 500, Windows 95, ThinkPad, iMac, G3, iBook, G3, PowerBook G4, and Windows XP.

You need to set Duo to the expanded “laptop” mode in order to fiddle with these old-fashioned devices. They come with keyboards that can be clicked, a command line that is usable, drawing programs, floppy disks, and even some desktop games. But it’s not just an exhibition of old computers—it also has gaming elements, because you can search for hidden files and secret commands to win medals.

Sky Guide

Sky Guide is that classic stargazing app. Sometimes when I'm enjoying nature outdoors, I'll open it to figure out whether that bright spot in the sky is a star or a planet, or what the constellation next to Orion is called.

Apple also specifically mentioned this company in its press release introducing all the new Duo optimized apps, which is not hard to understand. The larger display screen when Duo is unfolded makes tracking the night sky much easier, providing a more immersive, edge-to-edge map that also moves with your location and orientation. I definitely plan to bring it along on my next camping trip or night walk.

MD Vinyl

Maybe I just have no resistance to retro music apps, but the Duo optimized version of the music player from MD Vinyl really didn't disappoint me.

The mini-components of this app have long been on my main screen (which uses the iPhone theme) due to their aesthetic appeal. It includes a small rotating record, as well as an interface that displays the title of the song you are playing and the artist's name, with playback controls located beside it.

Now, at iPhone Duo, virtual vinyl records can take up more screen space. You can even pick up the arm of the turntable and place it on the rotating record to start playing, or remove it to stop the music.

P Token Issuance Cam

Before Duo, the P-token issuance Cam provided a small and fun camera application that allowed users to take virtual Polaroid-style photos. These photos would pop out from the pill-shaped opening at the top of the phone's Dynamic Island (the screen's top portion). You could also shake the photo to make it develop faster, then add stickers and share it with friends.

Now, after optimization by iPhone and Duo, the issuance of P tokens Cam can be used in both open and closed states on mobile devices; when closed, you will have more screen space to view your photo library after taking pictures.

Honorary nomination, I guess: Toastie

Do you still remember when iPhone was first launched, there was an app that made it seem like you were drinking beer whenever you tilted your phone towards your mouth? Toastie is that very same absurd experience from the iPhone Duo versions.

Of course, I wouldn't call Toastie a "killer app"; it's just too ridiculous. But if you dare to give this expensive device to a child, it could be a rather interesting toy.

This app is playfully described as “the world’s most expensive toaster” (alluding to the ridiculously high price of Duo). You can make a slice of toast according to the recipe, add butter, cheese, or many other toppings, and then close the Duo to “bake” the toast.

If you turn on your phone too early, the toast won't be cooked properly, and you won't be able to get the five-star rating you desire.

Of course you don't need this app, but since you've already spent a good amount of money on your phone itself, what's the big deal with spending an extra $2.99?

As more developers will obtain iPhone and Duo in the coming weeks, we expect to see even more interesting applications emerge.