To install and Setup Unity in Your Pc/Computer or Mac

Download Unity Engine Here:
Unity 5

System Requirements For Unity Game Engine

For Windows Users:-

Win 7,8,10
Win Xp & Vista are not supported

Gpu/Graphic Card:

Shader Model 3.0/Directx 9 or 11

For Mac Users:-

Mac OS X 10.8+

For Android and IOS Game Development:-

For Android we need
1 Android Sdk and ndk
2 Java Developement Kit (Jdk)
For advanced versions we need android NDK unity 4 and above

For IOS we need
1 Mac computer running minimum OS X 10.9.4
2  Xcode 7.0 or higher

For Windows we need

Windows 8.1 (64-bit) and corresponding Visual Studio and platform SDK