OnePlus has been rumored to be developing a successor to its "flagship killer" OnePlus One and it appears that the next-gen phone dubbed OnePlus Two could be released very soon, as the company has sent out an official invite for an event to be held on April 20, with the tagline 'Anything could happen,' indicating a major launch.

OnePlus One had offered users top-of-the-line specifications at half the price of smartphones being sold by the big players in the market. So OnePlus Two is expected to feature even better hardware specifications and features than its predecessor to provide users with improved mobile performance and flexibility.

The company has not revealed any hardware specifications of the OnePlus Two, though its CEO Carl Pei had announced in January this year that the upcoming smartphone would be extremely different and surprise people. But earlier rumors have suggested that the OnePlus Two could come with a 5.5-inch display having a resolution of 2,560 X 1,440 pixels and would be powered by a Snapdragon 810 processor with 3GB of RAM and 3,100 mAh battery. Some media reports had indicated that the smartphone would run on Google's Android 5.0 Lollipop operating system, while other sources had claimed that it would run on the company's custom platform.

Instead of the polycarbonate frame of its predecessor, the OnePlus Two is rumored to sport a metallic frame made of premium materials, which could result in the next-gen OnePlus phone being sold at a higher-than-expected price.

A recent report had suggested that OnePlus Two would be accompanied by a second phone, which is expected to be a cheaper model. OnePlus Two was rumored to be launched in Q3 2015, while the budget smartphone was expected to be released before the end of the year. However, OnePlus has now sent out an official invite for an event to be held on April 20, with a Google Plus post that says, "You're Invited" to something on April 20, but we aren't quite sure what that something might be. From here on out, anything could happen."

OnePlus sold over 1 million smartphones in 2014 and the company now plans to sell 3-5 million units in 2015 and a whopping 10 million units by the end of 2016.