Your choice between the Hyperkin SmartBoy and the RetroN Sq comes down to one question: do you want to play Game Boy cartridges on the go using your Android phone’s screen, or do you want to kick back and run them on a TV? The SmartBoy clips onto a compatible USB-C Android device and uses the phone’s display, while the RetroN Sq is a standalone cube-shaped console that outputs at 720p over HDMI. Neither does everything, but each does its one thing well enough to be worth considering.
Both accessories accept physical Game Boy and Game Boy Color cartridges, which means they serve the same collector audience: people who own the carts and want a better screen than a worn-out DMG LCD. Where they split is format, price, and how much setup friction you are willing to tolerate.
What cartridges does each device actually support?
Game Boy (DMG) and Game Boy Color cartridges work reliably on both devices. That covers the vast majority of the classic library, from Tetris and Pokémon Red to Zelda: Oracle of Ages.
Game Boy Advance is where the gap opens up. The SmartBoy officially supports only GB and GBC cartridges. GBA apps from Google Play can be loaded separately, but the cartridge slot itself does not accept GBA carts. The RetroN Sq accepts all three cartridge formats, though GBA support launched as a beta feature with known framerate problems. Firmware version 1.2 addressed most of those issues, and reviewers who tested updated units found that GBA titles ran smoothly after dropping the frame-skip setting in the bundled mGBA emulator from 4 to 0. That tweak requires plugging a USB keyboard into the console and pressing F1, which is not exactly plug-and-play. If your collection is heavy on GBA titles like Golden Sun or Advance Wars, the RetroN Sq is the only option of the two, with the understanding that some light configuration may be needed.
| Feature | SmartBoy | RetroN Sq |
|---|---|---|
| Game Boy (DMG) | Yes | Yes |
| Game Boy Color | Yes | Yes |
| Game Boy Advance | No (cartridge) | Yes (beta, firmware-dependent) |
| NTSC and PAL carts | Yes | Yes |
Does the RetroN Sq actually look good on a TV?
The RetroN Sq outputs at 720p over HDMI at 60fps, and you can toggle between 4:3 and 16:9 aspect ratios using a physical switch on the back. Neither ratio is technically correct for the original Game Boy screen (which was closer to 1:1), so there is a slight stretch either way. Most players find 4:3 acceptable; dedicated purists will notice it. The console runs open-source software including mGBA, and Game Boy and Game Boy Color titles look clean and sharp at that resolution. Pixel art scales up well at 720p, and the chunky pixels are part of the charm for most retro fans.
The SmartBoy, by contrast, outputs to your phone’s own display. Upscaling is handled by the Android emulator you choose (My OldBoy is the default). On a flagship screen like a Samsung Galaxy S8 or newer, the result is genuinely sharp and bright. The phone’s AMOLED panel is objectively superior to any original Game Boy LCD. But the image stays on a 5- to 6-inch screen, which is the point: this is a portable solution.
How portable is the SmartBoy compared to the RetroN Sq?
The SmartBoy is the only portable option of the two. It clips onto your Android phone via USB-C, adds a D-pad, A/B/Start/Select buttons, and shoulder buttons around the sides, and draws power directly from the phone. No batteries required. Phone size compatibility runs from 5.2 to 6.4 inches, and the device was designed with Samsung’s Galaxy S8 line as the primary target. Compatibility with non-Samsung Android phones varies and is not guaranteed.
The RetroN Sq is a home console. It is small enough to fit in a bag, but it needs HDMI output to a display and USB-C power from an adapter. You are not playing this on the bus. If you want portability, the SmartBoy wins by default.
One real-world friction point with the SmartBoy: setup requires two apps (the SmartBoy companion and a Game Boy emulator like My OldBoy), and the companion app’s menus are fiddly with the phone inserted. First-time setup typically takes around 10 minutes and requires following instructions carefully. After that, the experience is smoother.
How do the prices compare, and which offers more value?
The SmartBoy launched at $49.99 and is frequently found at lower prices through secondary markets. The RetroN Sq launched at around $74.99 and includes an HDMI cable, a USB-C power cable with adapter, and a wired USB “Scout” controller with a 10-foot cable. The controller is a repurposed SNES-style pad with four action buttons, which is two more than any Game Boy ever had, but it is comfortable and responsive after firmware updates resolved early input-lag complaints.
| SmartBoy | RetroN Sq | |
|---|---|---|
| Price (launch) | $49.99 | ~$74.99 |
| Display | Phone screen | TV via 720p HDMI |
| Included controller | No (phone buttons) | Yes (wired USB Scout) |
| GBA support | No | Yes (updated firmware) |
| Setup complexity | Moderate (2 apps) | Low (cartridge in, play) |
| Portability | Yes | No |
For a pure value calculation: the RetroN Sq costs more but includes everything needed to play on a TV, supports GBA cartridges, and requires less ongoing app management. The SmartBoy costs less but assumes you already own a compatible Android phone and are willing to manage emulator settings.
The Setup That Decides It
If you own a compatible USB-C Android phone and want to play Game Boy or Game Boy Color cartridges anywhere, the SmartBoy is the right call. It is cheaper, genuinely portable, and delivers a sharp image on a modern phone display.
If your cartridge collection includes GBA titles, or if you want to play on a TV without fussing with phone compatibility, the RetroN Sq is the better fit. It covers all three Game Boy formats in a single slot, outputs at 720p over HDMI, and ships with a controller. The GBA framerate issue that plagued early units has been largely resolved through firmware updates, so buyers in 2026 are in a better position than those who picked one up at launch. Hyperkin’s broader retro console lineup, including the Hyperkin RetroN 5, shows the same philosophy carried into a multi-format machine if you want to go further than just the Game Boy library.
The RetroN Sq is the pick for anyone who cares about GBA support and TV output. The SmartBoy is the pick if portability is the whole point.
Frequently Asked Questions
Does the Hyperkin SmartBoy work with iPhones?
No. The SmartBoy connects via USB-C and is designed exclusively for Android devices. Apple’s iPhone lineup uses a different port and is not supported. Officially, Hyperkin designed the SmartBoy for Samsung’s Galaxy S8 line and up, though other USB-C Android phones may work with varying results.
Can the RetroN Sq save games to the cartridge itself?
No. The RetroN Sq stores save files on its internal microSD card rather than writing them back to the cartridge. This means if you move a cartridge to a real Game Boy after playing on the RetroN Sq, your save progress will not carry over. Hyperkin states this is to prevent file corruption, but it is a meaningful limitation for players who switch between devices.
Does the Hyperkin SmartBoy require batteries?
No. The SmartBoy draws power directly from the phone it attaches to via the USB-C connection, so no separate batteries or power adapter are needed. Your phone’s battery handles everything, which means longer sessions will drain it faster than normal.
What emulator does the RetroN Sq use for GBA games?
The RetroN Sq runs mGBA, an open-source Game Boy Advance emulator, under the hood. By default, the frame-skip setting is set to 4, which causes stuttering. Connecting a USB keyboard and pressing F1 opens the mGBA settings menu, where dropping frame-skip to 0 and saving with ESC resolves most GBA performance issues on updated firmware.
Is the Hyperkin SmartBoy compatible with Game Boy Advance cartridges?
No. The SmartBoy’s cartridge slot accepts Game Boy and Game Boy Color cartridges only. GBA apps from Google Play can be used separately, but the physical slot does not fit GBA carts. For GBA cartridge support, the RetroN Sq is the only Hyperkin option of the two reviewed here.