External Build System Configuration
If you don't want to use Visual Studio IDE to compile your projects (f.e. you prefer Sublime text editor), you can build your game without it.
Grabbing the MSBuild
First, you need to get the MSBuild. This tool is part of .NET Framework, also as part of MSVS installation. Path can be different according to your OS version, f.e. C:\Program Files (x86)\MSBuild\12.0\Bin
I recommend to add its path to the PATH system variable to make your life easier.
Building the game
This command will build the Shooter Game example (you need to generate .sln files first):
msbuild "<MY_DOCUMENTS>\Unreal Projects\ShooterGame\ShooterGame.sln" /p:configuration=Development /p:platform=Windows
Use /t:rebuild to completely rebuild the game solution.
You can use this tool with whatever IDE or text editor you want.