When you buy a smartwatch, you don't have any choice but to use the operating system it comes with out of the box. Whether that's Apple's watchOS, Fitbit OS, Wear or Samsung's Tizen, there's no budging from that.
Until, that is, AsteroidOS turned up. Several years in the making and the passion project of French computer scientist Florent Revest, the open-source software built for smartwatches has now hit version 1.0 after a long period of development and is ready for intrigued Wear smartwatch owners to play around with.
Read this: Essential Wear tips and tricks to try out
If you've got a compatible Wear OS smartwatch, you can try it out, and even get it running alongside Google's smartwatch software so you can switch as you prefer.
We've explained the quickest way to get Asteroid OS installed. Things might get a bit technical, so have a good read through the how-to below before you attempt to have a got at it.
Compatible watches
You can't just slap AsteroidOS on any watch, because it needs to be customised to fit. Right now, the software works with the original Asus ZenWatch, the ZenWatch 2, the ZenWatch 3, the LG G Watch, the LG G Watch Urbane, the LG G Watch R, and the Sony Smartwatch 3.
On top of that, it's only compatible with Android phones — you're not able to use a watch running AsteroidOS with an iPhone at the moment.
Click here to see a list of compatible watches on the AsteroidOS site, together with a useful FAQ (more models may get added as time goes on). A list of watches that might be supported in the future can be found here, and if you're interested in getting the AsteroidOS software ported to a particular watch, guidance on that can be found here.
In this guide we're going to show you how to get AsteroidOS up and running on a Sony Smartwatch 3, though the process should be similar for the other watches. Instructions for individual devices are available on the AsteroidOS site.
Laying the foundations
This can be done on Linux, but we're going to show you how to do it on Windows here: Windows is really your best option if you're thinking of installing AsteroidOS.
First, you need to download and install the AsteroidOS files specific to the smartwatch you've got – head here and click on the relevant watch model, then download the two AsteroidOS files listed on the left. Make sure they've saved in the default Downloads folder in Windows, as this will be important later.
You also need to download and install the Android Debug Bridge (ADB) driver, and a couple of Android developer tools, all of which can be found on the same page as your AsteroidOS files. Install the driver into the default suggested folder, and the developer tools into a folder of your choice.
Then, open a command line window in the folder where you extracted the developer tools to — open the folder in File Explorer, hold down Shift and right-click inside the window, then select Open PowerShell window here.
Now you need to unlock the bootloader on your Wear OS watch, which basically makes it more amenable to having a second operating system installed on it. To do this, find the Settings menu, go right down to the About page, and then tap the Build number seven times to enable developer options.
Swipe right to go back to Settings, then choose the newly visible Developer options menu (below About). Find the ADB debugging option and enable it.
Installing AsteroidOS
You're now ready to get AsteroidOS on your watch. Connect your wearable up to your Windows machine with the USB cable it came with.
In the command line (or PowerShell) window you opened earlier, type the following text, hitting Enter after each line. Doing this may well void your device's warranty, by the way, so proceed at your own risk:
.\adb reboot bootloader
.\fastboot oem unlock
That unlocks your watch ready for a new OS. If you want to replace Wear OS with AsteroidOS completely, these are the commands you need to type into Windows next (hitting Enter after each line):
.\ext2simg %systemdrive%%homepath%\Downloads\asteroid-image-tetra.ext4 %systemdrive%%homepath%\Downloads\asteroid-image-tetra.ext4.simg
.\fastboot flash userdata %systemdrive%%homepath%\Downloads\asteroid-image-tetra.ext4.simg
.\fastboot flash boot %systemdrive%%homepath%\Downloads\zImage-dtb-tetra.fastboot
.\fastboot continue
If you'd rather dual-boot your smartwatch, use this command (then Enter):
.\adb push -p %systemdrive%%homepath%\Downloads\asteroid-image-tetra.ext4 /sdcard/asteroidos.ext4
You probably want to give AsteroidOS a trial run before switching over to it completely, but the dual-boot option does come with some downsides. Every time you restart your watch, it'll go back to Wear OS; if you want to boot into AsteroidOS then you need to open up your command line window again and type this (Enter after each line):
.\adb reboot bootloader
.\fastboot boot %systemdrive%%homepath%\Downloads\zImage-dtb-tetra.fastboot
Not the most convenient process, depending on how often you reset your watch, but probably the way to go to begin with if you're not sure you want to completely commit to the AsteroidOS cause.
Having problems?
With the quality and detail of the instructions on the AsteroidOS website, you shouldn't run into any problems. If you do, double-check the simple stuff first: have you typed in all the commands correctly? Is your watch connected?
Considering there are so many devices you could be using, so many parts to the process, and so many different ways that you might have Windows set up, we can't give you much specific help on resolving issues except to say run as many web searches as you can if you get stuck — and be as specific as possible in those searches.
One generic tip we can give you is to keep Device Manager open at all times and make sure your computer is still 'seeing' your smartwatch after you've enabled debugging and switched to the Fastboot mode. If the device appears with a yellow exclamation point over it then you might have a driver issue.
You'll find a ton of helpful pointers and troubleshooting tips online. We found this page on XDA Developers and this video particularly useful in finally getting our AsteroidOS installation over the line, but your mileage is likely to vary. Hopefully, you won't come across any issues at all.
How we test