Unstream is a popular third-party application for Windows 10 devices that allows users to access Twitch content on their Windows 10 PCs and mobile devices.
As a third-party app it offers quite a lot in terms of features and functionality. You can connect it to your Twitch account, favourite streams, view streams, look at the top streams and see who you're following. It also integrates with Twitch chat and offers plenty of customisation within its Settings menu.
Demand for an official, universal app for Twitch has grown; an idea on Twitch's UserVoice forum has gained over 1,000 votes in the last 24 hours and continues to increase. This shows that people are calling for an official app from Twitch.
The developer of Unstream, Travis Liew, took to one of the Reddit threads about an official Twitch app and declared that he would offer Twitch the code for his app. Travis said that he is "happy to hand over" the code for his app, as long as it would "help bring the official app".
So far Twitch hasn't commented on the proposal for a universal app, nor do there appear to be any current plans for one. This doesn't mean that they aren't working on, or planning an app, as momentum for universal apps has grown recently, with services such as Netflix, 4Shared, TED and many more having released universal apps in the past couple weeks.