Latest update: The new software is confirmed: it's set to be Oxygen OS.
The OnePlus One came out of nowhere as the first product of a new company, but it didn't disappoint, thanks to high end specs and a surprisingly low price tag.
One of the biggest complaints we could level at it was how hard it was to get hold of at launch and when that's the biggest problem a phone is facing you know you've got a winner on your hands.
But while there were no expectations for the One hopes are sky high for the OnePlus 2, so it's got a lot to live up to.
Cut to the chase
What is it? The Chinese firm's next cut-price flagship smartphone
When is it out? Potential launch on June 1 2015
What will it cost? Hopefully around half the price of rival flagships
OnePlus 2 release date
OnePlus has taken to Twitter and teased us with a cryptic message: "We're always looking for ways to shake up the tech industry. And we think it's time for change. Find out more June 1."
The message was accompanied by the image above, showing the OnePlus One handset being erased with the words "Time to change" below - it's all pointing towards the launch of the OnePlus Two if you ask us.
OnePlus 2 price
The original OnePlus One was a bit of a steal at $299, £229 for the 16GB model and just $349, £269 for the 64GB handset - we're hoping the OnePlus Two will be just as affordable.
There's good news here, as the CEO of OnePlus has claimed the OnePlus 2 will cost around ¥2499 (around $400, £265, AU$500).
News and rumors
The company's CEO has mentioned the OnePlus Two will come with a Snapdragon 810 processor, which matches a benchmark which lists it as having a Snapdragon 810 chip and 3GB of RAM, just like the HTC One M9.
That's similar but not identical to previous rumblings that specs will include a 5.5-inch QHD screen, a Snapdragon 810 processor, 4GB of RAM and a 3300 mAh battery, while other reports point to a 16MP main camera and a 5MP front-facing snapper and we've even heard word that it might have a premium metal build.
We've also heard that the OnePlus 2 might have a similar design to the Oppo Find 7 and come with a "laser focus fingerprint identification system" embedded in the home button. A fingerprint scanner would certainly be good, but there's a worry that it could drive the price up.
OnePlus has now confirmed the move to OxygenOS but has yet to confirm whether the latest Android software will be involved.
OxygenOS has now landed and is basically a streamlined take on Android, with added off-screen gesture controls, which let you turn the screen on and launch apps with a gesture.
OxygenOS also includes a built in file manager and more customization options, such as customizable quick settings and the ability to switch between hardware and software navigation keys.
Perhaps most intriguingly of all though the OnePlus 2 is apparently set to 'surprise people'. Of course all the rumors that we've heard could turn out to be false and there's still plenty that we don't know, so here's what we want to see.
OnePlus 2: what we want to see
The OnePlus One was a great device with high-end specs at an affordable price, but there's still room for improvement. Here's what we want to see from the OnePlus Two.
1. A more premium build
The OnePlus One is a top tier handset, but it doesn't look like a top tier handset so we really hope the OnePlus Two will have a more premium build.
The obvious choice here is metal, which there are rumors we'll see this time around, but we'd be just as happy with something like bamboo. The OnePlus One briefly had bamboo back covers available, but manufacturing issues meant they were discontinued and this time we'd like to see them included as standard.
2. A similarly low price
One of the biggest selling points of the OnePlus One is its relatively low price tag, as it starts at just £229, $299. That price hasn't gone down since launch, so it's slightly less impressive now than it once was, but it's less than half the cost of most flagships.
If the specs and build are improved as is likely then there's a good chance that the OnePlus 2 will also be more expensive, but if it is then we hope not by much. Thankfully it looks like it might still be affordable.
3. A microSD card slot
Cut corners are always likely to be necessary when delivering a phone as good value as the OnePlus One and one of them was the omission of a microSD card slot.
We can't be too hard on it when phones twice its price, like the Samsung Galaxy S6, also lack such a slot, but we'd love to see one included in the OnePlus Two so that storage is less limited.
Or at the very least an option for more internal memory. The 64GB available in some versions of the OnePlus One is pretty generous, but we're sure it could be increased to 128GB.
4. A removable battery
Another slight disappointment with the OnePlus One was that the battery isn't removable. That's the case with a lot of phones and the OnePlus One does at least have quite good battery life.
But if you're a power user it's nice to know you can swap the battery out if needed and perhaps even more importantly it means you can replace the battery when yours wears out rather than having to buy a whole new phone.
5. Even better specs
With its 2.5GHz quad-core Snapdragon 801 processor and 3GB of RAM the OnePlus One is undeniably a powerful phone and back when it launched in June 2014 it was one of the most powerful handsets on the planet.
But by the time the OnePlus Two launches it will be at least a year old and time moves fast in the tech world, with octa-core processors now the norm among flagships. So at a minimum we hope the OnePlus 2 will keep pace with the latest and greatest phones around.
The obvious setup for that would be to have an octa-core Snapdragon 810 processor and 3GB of RAM, just like the HTC One M9, but if OnePlus feels like it wants to overpower the competition we won't complain. 4GB of RAM anyone?
6. The same size screen
This might seem odd but we don't want the screen to get any bigger. The OnePlus One already has a 5.5-inch display and that's pushing the limits of usability as it is. In fact we wouldn't complain if the screen on the OnePlus 2 was slightly smaller.
That's not to say that we wouldn't like to see improvements though. OnePlus could always up the resolution to QHD (assuming the battery life doesn't take too much of a hit) and as good as the screen on the One is things like contrast and colour reproduction can always be improved.
7. A top flight camera
The 13MP shooter on the OnePlus One is more than adequate but even at launch it wasn't one of the best smartphone snappers around and the gulf has only widened since.
So with the OnePlus 2 we'd like to see some improvements. The OnePlus One seems a little slow to autofocus, so a fix for that would be appreciated, whether through a new system like a laser autofocus or just through software optimisation.
More megapixels and optical image stabilisation would both be nice too, but they don't always lead to better photos, which is what we want. How that will be achieved is down to OnePlus to figure out.
8. A powerful UI
The UI on the OnePlus One was worthy of special mention, because it used CyanogenMod, which on the surface looks quite close to stock Android, but there's a whole lot of power and customisation options tucked away for more adventurous users.
Sadly OnePlus has had a bit of a falling out with Cyanogen, so a new home-grown UI dubbed OxygenOS will be replacing it on the OnePlus 2 and we hope it will be every bit as powerful and intuitive.
9. Water and dust proofing
Water and dust proofing is a feature which we've never felt is essential on phones as we stopped pond diving years ago, but it's still nice to have if it doesn't come at the expense of anything else and it would be one more bullet point in the OnePlus 2's favour.
We doubt we'll see it, mostly because it could push the cost up and a low price surely takes priority, but also because a metal build is looking likely and not many metal phones seem to be waterproof.
10. A killer feature
Price and specs go a long way towards selling a smartphone, but for the OnePlus Two to really stand out and not just feel like a rehash of the OnePlus One a big feature would help.
That could take any number of forms. OnePlus could follow other manufacturer's leads and have a curved screen like the Samsung Galaxy S6 Edge and LG G Flex 2, or it could pack in serious fitness credentials with a heart rate monitor and the tools to track your progress. Or it could add a fingerprint scanner like Apple and Samsung have been doing. In fact a fingerprint scanner is now rumored.
But to stand out even more it could include something we've not seen anywhere else. Perhaps a retina scanner for example.
It probably won't have a feature that big, because cost is key, but if it did and if the cost could still be kept down then the OnePlus 2 could be a true flagship killer.