superDisplay is described as 'turns your Android device into a portable USB display for your Windows 10 PC. Duplicate or extend your screen simply by plugging in your phone or tablet'. There are six alternatives to superDisplay for a variety of platforms, including Mac, Windows, iPad, Android and iPhone. The best alternative is Duet Display. It's not free, so if you're looking for a free alternative, you could try Weylus. Other great apps like superDisplay are TwomonUSB (Paid), Astropad (Paid), EasyCanvas (Paid) and Air Stylus (Paid).